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1.  Personal History of Prostate Cancer and Increased Risk of Incident Melanoma in the United States 
Journal of Clinical Oncology  2013;31(35):4394-4399.
Purpose
Steroid hormones, particularly androgens, play a major role in prostatic carcinogenesis. Personal history of severe acne, a surrogate for higher androgen activity, has been associated with an increased risk of prostate cancer (PCa), and one recent study indicated that severe teenage acne was a novel risk factor for melanoma. These findings suggest a possible relationship between PCa and risk of melanoma. We prospectively evaluated this association among US men.
Methods
A total of 42,372 participants in the Health Professionals' Follow-Up Study (HPFS; 1986 to 2010) were included. Biennially self-reported PCa diagnosis was confirmed using pathology reports. Diagnosis of melanoma and nonmelanoma skin cancer (NMSC) was self-reported biennially, and diagnosis of melanoma was pathologically confirmed. We sought to confirm the association in 18,603 participants from the Physicians' Health Study (PHS; 1982 to 1998).
Results
We identified 539 melanomas in the HPFS. Personal history of PCa was associated with an increased risk of melanoma (multivariate-adjusted hazard ratio [HR], 1.83; 95% CI, 1.32 to 2.54). Although we also detected a marginally increased risk of NMSC associated with PCa (HR, 1.08; 95% CI, 0.995 to 1.16), the difference in the magnitude of the association between melanoma and NMSC was significant (P for heterogeneity = .002). We did not find an altered risk of melanoma associated with personal history of other cancers. The association between PCa and risk of incident melanoma was confirmed in the PHS (HR, 2.17; 95% CI, 1.12 to 4.21).
Conclusion
Personal history of PCa is associated with an increased risk of melanoma, which may not be entirely a result of greater medical scrutiny.
doi:10.1200/JCO.2013.51.1915
PMCID: PMC3842907  PMID: 24190118
2.  Prediagnostic Body Mass Index and Pancreatic Cancer Survival 
Journal of Clinical Oncology  2013;31(33):4229-4234.
Purpose
Although obesity is associated with increased incidence of pancreatic cancer, studies have not prospectively evaluated prediagnostic body mass index (BMI) and survival.
Patients and Methods
We analyzed survival by prediagnostic BMI assessed in 1986 among 902 patients from two large prospective cohorts diagnosed from 1988 to 2010. We estimated hazard ratios (HRs) for death using Cox proportional hazards models, with adjustment for age, sex, race/ethnicity, smoking, diagnosis year, and stage. We evaluated the temporal association of BMI with survival by grouping reported BMI by 2-year lag-time intervals before diagnosis.
Results
The multivariable-adjusted HR for death was 1.53 (95% CI, 1.11 to 2.09) comparing patients with BMI ≥ 35 kg/m2 with those with BMI < 25 kg/m2 (P trend = .001), which was similar after adjustment for stage. The association of BMI with survival was stronger with longer lag times between reported BMI and cancer diagnosis. Among patients with BMI collected 18 to 20 years before diagnosis, HR for death was 2.31 (95% CI, 1.48 to 3.61; P trend < .001), comparing obese with healthy-weight patients. No statistically significant differences were seen by cohort, smoking status, or stage, although the association was stronger among never-smokers (HR, 1.61; 95% CI, 1.01 to 2.57; P trend = .002) than ever-smokers (HR, 1.36; 95% CI, 0.86 to 2.15; P trend = .63), comparing BMI ≥ 35 kg/m2 with BMI < 25 kg/m2. Higher prediagnostic BMI was associated with more advanced stage at diagnosis, with 72.5% of obese patients presenting with metastatic disease versus 59.4% of healthy-weight patients (P = .02).
Conclusion
Higher prediagnostic BMI was associated with statistically significantly decreased survival among patients with pancreatic cancer from two large prospective cohorts.
doi:10.1200/JCO.2013.51.7532
PMCID: PMC3821012  PMID: 24145341
3.  Vitamin D Receptor Protein Expression in Tumor Tissue and Prostate Cancer Progression 
Journal of Clinical Oncology  2011;29(17):2378-2385.
Purpose
Data suggest that circulating 25-hydroxyvitamin D [25(OH)D] interacts with the vitamin D receptor (VDR) to decrease proliferation and increase apoptosis for some malignancies, although evidence for prostate cancer is less clear. How VDR expression in tumor tissue may influence prostate cancer progression has not been evaluated in large studies.
Patients and Methods
We examined protein expression of VDR in tumor tissue among 841 patients with prostate cancer in relation to risk of lethal prostate cancer within two prospective cohorts, the Physicians' Health Study and Health Professionals Follow-Up Study. We also examined the association of VDR expression with prediagnostic circulating 25(OH)D and 1,25-dihydroxyvitamin D levels and with two VDR single nucleotide polymorphisms, FokI and BsmI.
Results
Men whose tumors had high VDR expression had significantly lower prostate-specific antigen (PSA) at diagnosis (P for trend < .001), lower Gleason score (P for trend < .001), and less advanced tumor stage (P for trend < .001) and were more likely to have tumors harboring the TMPRSS2:ERG fusion (P for trend = .009). Compared with the lowest quartile, men whose tumors had the highest VDR expression had significantly reduced risk of lethal prostate cancer (hazard ratio [HR], 0.17; 95% CI, 0.07 to 0.41). This association was only slightly attenuated after adjustment for Gleason score and PSA at diagnosis (HR, 0.33; 95% CI, 0.13 to 0.83) or, additionally, for tumor stage (HR, 0.37; 95% CI, 0.14 to 0.94). Neither prediagnostic plasma vitamin D levels nor VDR polymorphisms were associated with VDR expression.
Conclusion
High VDR expression in prostate tumors is associated with a reduced risk of lethal cancer, suggesting a role of the vitamin D pathway in prostate cancer progression.
doi:10.1200/JCO.2010.30.9880
PMCID: PMC3107752  PMID: 21537045
5.  Genetic Variation across C-Reactive Protein and Risk of Prostate Cancer 
The Prostate  2014;74(10):1034-1042.
Background
Inflammation has been hypothesized to play an important etiological role in the initiation or progression of prostate cancer. Circulating levels of the systemic inflammation marker C-reactive protein (CRP) have been associated with increased risk of prostate cancer. We investigated the role of genetic variation in CRP and prostate cancer, under the hypothesis that variants may alter risk of disease.
Methods
We undertook a case-control study nested within the prospective Physicians' Health Study among 1,286 men with incident prostate cancer and 1,264 controls. Four single-nucleotide polymorphisms (SNPs) were selected to capture the common genetic variation across CRP (r2>0.8). We used unconditional logistic regression to assess the association between each SNP and risk of prostate cancer. Linear regression models explored associations between each genotype and plasma CRP levels.
Results
None of the CRP SNPs were associated with prostate cancer overall. Individuals with one copy of the minor allele (C) in rs1800947 had an increased risk of high-grade prostate cancer (OR: 1.7; 95% CI: 1.1–2.8), and significantly lower mean CRP levels (p-value <0.001), however, we found no significant association with lethal disease. Mean CRP levels were significantly elevated in men with one or two copies of the minor allele in rs3093075 and rs1417939, but these were unrelated to prostate cancer risk.
Conclusion
Our findings suggest that SNPs in the CRP gene are not associated with risk of overall or lethal prostate cancer. Polymorphisms in CRP rs1800947 may be associated with higher grade disease, but our results require replication in other cohorts.
doi:10.1002/pros.22820
PMCID: PMC4063346  PMID: 24844401
CRP SNPs; prostate cancer; inflammation
6.  SLEEP DURATION IN MIDLIFE AND LATER LIFE IN RELATION TO COGNITION 
Background/Objectives
Sleep might influence brain health in older adults; however, epidemiologic research in this area is limited. We evaluated associations of sleep duration at midlife and later life, and change in sleep duration over time, with cognitive function in older women.
Design
Participants reported sleep duration in 1986 and 2000, and a subgroup of older participants began cognitive testing in 1995–2001; follow-up testing was conducted three times, at two-year intervals.
Setting
Prospective Nurses’ Health Study cohort.
Participants
15,385 female nurses, aged ≥70 years, free of stroke and depression at the initial cognitive assessment.
Measurements
Validated, telephone-based cognitive battery to measure cognitive function; we averaged the four repeated assessments over a six-year period to estimate overall cognition at older ages, and also evaluated trajectories of cognitive change over follow up.
Results
Extreme sleep durations in later life were associated with worse average cognition (p-value for the quadratic term<0.001 for a global score averaging all six cognitive tests). For example, women sleeping ≤5 hours/day had worse global cognition than those sleeping 7 hours/day, as did women sleeping ≥9 hours/day; differences were equivalent to nearly two additional years of age. Associations were similar, though slightly attenuated, for sleep duration in midlife. Also, women whose sleep duration changed by ≥2 hours/day over time had worse cognition than women with no change in sleep duration (e.g., for the global score, p-value for the quadratic term<0.001). Sleep duration was not associated with women’s trajectories of cognitive function over six years (i.e., cognitive decline), which might be attributable to relatively short follow up for detecting cognitive decline.
Conclusions
Extreme sleep durations at both midlife and later life, and extreme changes in sleep duration over time, appear to be associated with worse cognitive status in older women.
doi:10.1111/jgs.12790
PMCID: PMC4188530  PMID: 24786726
sleep; cognition; epidemiology; cohort study
7.  Plasma antioxidants, genetic variation in SOD2, CAT, GPX1, GPX4, and prostate cancer survival 
Background
Antioxidants may reduce risk of aggressive prostate cancer, and single nucleotide polymorphisms (SNPs) in antioxidant genes may modify this association.
Methods
We used Cox proportional hazards regression to examine circulating prediagnostic alpha-tocopherol, gamma-tocopherol, and lycopene; SNPs in SOD2 (n=5), CAT (n=6), GPX1 (n=2), GPX4 (n=3); and their interactions and risk of lethal prostate cancer among 2,439 men with nonmetastatic prostate cancer in the Health Professionals Follow-up Study and Physicians’ Health Study.
Results
We observed 223 events over a median follow-up of 10 years. Higher alpha-tocopherol levels were associated with lower risk of lethal prostate cancer (hazard ratio (HR) 3rd v. 1st quartile (Q): 0.51; 95% confidence interval (CI): 0.30, 0.89; HR 4th v. 1st Q: 0.68; 95% CI: 0.41, 1.13; p-trend: 0.02). Men homozygous for the less common allele (G) at rs3746165 in GPX4 had a 35% lower risk of lethal prostate cancer compared to men homozygous for the more common allele (A) (HR: 0.65; 95% CI: 0.43, 0.99). Among men homozygous for the less common allele in rs3746165, high gamma-tocopherol levels were associated with a 3.5-fold increased risk of lethal prostate cancer (95% CI: 1.27, 9.72; p-value: 0.02; interaction p-value 0.01).
Conclusions
Among men with nonmetastatic prostate cancer, higher circulating prediagnostic alpha-tocopherol may be associated with lower risk of developing lethal disease. Variants in GPX4 may be associated with risk of lethal prostate cancer, and may modify the relation between gamma-tocopherol and prostate cancer survival.
Impact
Circulating tocopherol levels and variants in GPX4 may affect prostate cancer progression.
doi:10.1158/1055-9965.EPI-13-0670
PMCID: PMC4047147  PMID: 24711484
tocopherol; lycopene; prostate cancer; survival; genetics
8.  Association of C-peptide and leptin with prostate cancer incidence in the Health Professionals Follow-Up Study 
Cancer causes & control : CCC  2014;25(5):625-632.
Purpose
Hyperinsulinemia is hypothesized to influence prostate cancer risk. Thus, we evaluated the association of circulating C-peptide, which is a marker of insulin secretion, and leptin, which is secreted in response to insulin and influences insulin sensitivity, with prostate cancer risk.
Methods
We identified prostate cancer cases (n=1,314) diagnosed a mean of 5.4 years after blood draw and matched controls (n=1,314) in the Health Professionals Follow-Up Study. Plasma C-peptide and leptin concentrations were measured by ELISA. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated taking into account the matching factors age and history of a PSA test before blood draw and further adjusting for body mass index, diabetes, and other factors.
Results
Neither C-peptide (quartile [Q]4 versus Q1: OR=1.05, 95% CI 0.82–1.34, p-trend=0.95) nor leptin (Q4 versus Q1: OR=0.85, 95% CI 0.65–1.12, p-trend=0.14) was associated with prostate cancer risk. Further, neither was associated with risk of advanced or lethal disease (N=156 cases; C-peptide: Q4 versus Q1, OR=1.18, 95% CI 0.69–2.03, p-trend=0.78; leptin: Q4 versus Q1, OR=0.74, 95% CI 0.41–1.36, p-trend=0.34).
Conclusions
In this large prospective study, circulating C-peptide and leptin concentrations were not clearly associated with risk of prostate cancer overall or aggressive disease. Well into the PSA era, our findings do not appear to be supportive of the hypothesis that hyperinsulinemia influences risk of total or aggressive prostate cancer.
doi:10.1007/s10552-014-0369-3
PMCID: PMC4028628  PMID: 24664287
Prostate cancer; C-peptide; leptin; nested case-control study; risk
9.  Mediterranean Diet and Prostate Cancer Risk and Mortality in the Health Professionals Follow-up Study 
European urology  2013;65(5):887-894.
Background
Prostate cancer (PCa) mortality rates are lower in the Mediterranean countries compared with northern Europe. Although specific components of the Mediterranean diet (Med-Diet) may influence PCa risk, few studies have assessed the traditional Med-Diet pattern with the risk of incident advanced or lethal PCa or with disease progression among men diagnosed with nonmetastatic PCa.
Objective
To determine whether the traditional Med-Diet pattern is associated with risk of incident advanced or lethal PCa and with PCa-specific and overall mortality among men with PCa.
Design, setting, and participants
We prospectively followed 47 867 men in the Health Professionals Follow-up Study followed from 1986 to 2010. The case-only analysis included 4538 men diagnosed with nonmetastatic PCa, followed from diagnosis to lethal outcome or to January 2010.
Outcome measurements and statistical analysis
We used Cox proportional hazards models to examine traditional and alternative Med-Diet scores in relation to PCa incidence outcomes (advanced and lethal disease). In a case-only survival analysis, we examined postdiagnostic Med-Diet and risk of lethal (metastases or PCa death) and fatal PCa as well as overall mortality among men diagnosed with nonmetastatic disease.
Results and limitations
Between 1986 and 2010, 6220 PCa cases were confirmed. The Med-Diet was not associated with risk of advanced or lethal PCa. In the case-only analysis, there was no association between the Med-Diet after diagnosis and risk of lethal or fatal PCa. However, there was a 22% lower risk of overall mortality (hazard ratio: 0.78; 95% confidence interval, 0.67–0.90; ptrend = 0.0007) among men with greater adherence to the Med-Diet after PCa diagnosis. We found similar associations for the alternative score.
Conclusions
A higher Med-Diet score was not associated with risk of advanced PCa or disease progression. Greater adherence to the Med-Diet after diagnosis of nonmetastatic PCa was associated with lower overall mortality.
doi:10.1016/j.eururo.2013.08.009
PMCID: PMC4157361  PMID: 23962747
Prostate cancer; Risk; Mortality; Mediterranean diet; Epidemiology
10.  Parent-of-origin specific allelic associations among 106 genomic loci for age at menarche 
Perry, John RB | Day, Felix | Elks, Cathy E | Sulem, Patrick | Thompson, Deborah J | Ferreira, Teresa | He, Chunyan | Chasman, Daniel I | Esko, Tõnu | Thorleifsson, Gudmar | Albrecht, Eva | Ang, Wei Q | Corre, Tanguy | Cousminer, Diana L | Feenstra, Bjarke | Franceschini, Nora | Ganna, Andrea | Johnson, Andrew D | Kjellqvist, Sanela | Lunetta, Kathryn L | McMahon, George | Nolte, Ilja M | Paternoster, Lavinia | Porcu, Eleonora | Smith, Albert V | Stolk, Lisette | Teumer, Alexander | Tšernikova, Natalia | Tikkanen, Emmi | Ulivi, Sheila | Wagner, Erin K | Amin, Najaf | Bierut, Laura J | Byrne, Enda M | Hottenga, Jouke-Jan | Koller, Daniel L | Mangino, Massimo | Pers, Tune H | Yerges-Armstrong, Laura M | Zhao, Jing Hua | Andrulis, Irene L | Anton-Culver, Hoda | Atsma, Femke | Bandinelli, Stefania | Beckmann, Matthias W | Benitez, Javier | Blomqvist, Carl | Bojesen, Stig E | Bolla, Manjeet K | Bonanni, Bernardo | Brauch, Hiltrud | Brenner, Hermann | Buring, Julie E | Chang-Claude, Jenny | Chanock, Stephen | Chen, Jinhui | Chenevix-Trench, Georgia | Collée, J. Margriet | Couch, Fergus J | Couper, David | Coveillo, Andrea D | Cox, Angela | Czene, Kamila | D’adamo, Adamo Pio | Smith, George Davey | De Vivo, Immaculata | Demerath, Ellen W | Dennis, Joe | Devilee, Peter | Dieffenbach, Aida K | Dunning, Alison M | Eiriksdottir, Gudny | Eriksson, Johan G | Fasching, Peter A | Ferrucci, Luigi | Flesch-Janys, Dieter | Flyger, Henrik | Foroud, Tatiana | Franke, Lude | Garcia, Melissa E | García-Closas, Montserrat | Geller, Frank | de Geus, Eco EJ | Giles, Graham G | Gudbjartsson, Daniel F | Gudnason, Vilmundur | Guénel, Pascal | Guo, Suiqun | Hall, Per | Hamann, Ute | Haring, Robin | Hartman, Catharina A | Heath, Andrew C | Hofman, Albert | Hooning, Maartje J | Hopper, John L | Hu, Frank B | Hunter, David J | Karasik, David | Kiel, Douglas P | Knight, Julia A | Kosma, Veli-Matti | Kutalik, Zoltan | Lai, Sandra | Lambrechts, Diether | Lindblom, Annika | Mägi, Reedik | Magnusson, Patrik K | Mannermaa, Arto | Martin, Nicholas G | Masson, Gisli | McArdle, Patrick F | McArdle, Wendy L | Melbye, Mads | Michailidou, Kyriaki | Mihailov, Evelin | Milani, Lili | Milne, Roger L | Nevanlinna, Heli | Neven, Patrick | Nohr, Ellen A | Oldehinkel, Albertine J | Oostra, Ben A | Palotie, Aarno | Peacock, Munro | Pedersen, Nancy L | Peterlongo, Paolo | Peto, Julian | Pharoah, Paul DP | Postma, Dirkje S | Pouta, Anneli | Pylkäs, Katri | Radice, Paolo | Ring, Susan | Rivadeneira, Fernando | Robino, Antonietta | Rose, Lynda M | Rudolph, Anja | Salomaa, Veikko | Sanna, Serena | Schlessinger, David | Schmidt, Marjanka K | Southey, Mellissa C | Sovio, Ulla | Stampfer, Meir J | Stöckl, Doris | Storniolo, Anna M | Timpson, Nicholas J | Tyrer, Jonathan | Visser, Jenny A | Vollenweider, Peter | Völzke, Henry | Waeber, Gerard | Waldenberger, Melanie | Wallaschofski, Henri | Wang, Qin | Willemsen, Gonneke | Winqvist, Robert | Wolffenbuttel, Bruce HR | Wright, Margaret J | Boomsma, Dorret I | Econs, Michael J | Khaw, Kay-Tee | Loos, Ruth JF | McCarthy, Mark I | Montgomery, Grant W | Rice, John P | Streeten, Elizabeth A | Thorsteinsdottir, Unnur | van Duijn, Cornelia M | Alizadeh, Behrooz Z | Bergmann, Sven | Boerwinkle, Eric | Boyd, Heather A | Crisponi, Laura | Gasparini, Paolo | Gieger, Christian | Harris, Tamara B | Ingelsson, Erik | Järvelin, Marjo-Riitta | Kraft, Peter | Lawlor, Debbie | Metspalu, Andres | Pennell, Craig E | Ridker, Paul M | Snieder, Harold | Sørensen, Thorkild IA | Spector, Tim D | Strachan, David P | Uitterlinden, André G | Wareham, Nicholas J | Widen, Elisabeth | Zygmunt, Marek | Murray, Anna | Easton, Douglas F | Stefansson, Kari | Murabito, Joanne M | Ong, Ken K
Nature  2014;514(7520):92-97.
Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality1. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation2,3, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P<5×10−8) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1/WDR25, MKRN3/MAGEL2 and KCNK9) demonstrating parent-of-origin specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and gamma-aminobutyric acid-B2 receptor signaling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition.
doi:10.1038/nature13545
PMCID: PMC4185210  PMID: 25231870
11.  Elevated circulating branched chain amino acids are an early event in pancreatic adenocarcinoma development 
Nature medicine  2014;20(10):1193-1198.
Most patients with pancreatic ductal adenocarcinoma (PDAC) are diagnosed with advanced disease and survive less than 12 months1. PDAC has been linked with obesity and glucose intolerance2-4, but whether changes in circulating metabolites are associated with early cancer progression is unknown. To better understand metabolic derangements associated with early disease, we profiled metabolites in prediagnostic plasma from pancreatic cancer cases and matched controls from four prospective cohort studies. We find that elevated plasma levels of branched chain amino acids (BCAAs) are associated with a greater than 2–fold increased risk of future pancreatic cancer diagnosis. This elevated risk was independent of known predisposing factors, with the strongest association observed among subjects with samples collected 2 to 5 years prior to diagnosis when occult disease is likely present. We show that plasma BCAAs are also elevated in mice with early stage pancreatic cancers driven by mutant Kras expression, and that breakdown of tissue protein accounts for the increase in plasma BCAAs that accompanies early stage disease. Together, these findings suggest that increased whole–body protein breakdown is an early event in development of PDAC.
doi:10.1038/nm.3686
PMCID: PMC4191991  PMID: 25261994
12.  Circadian clock genes and risk of fatal prostate cancer 
Cancer causes & control : CCC  2014;26(1):25-33.
Purpose
Circadian genes may be involved in regulating cancer-related pathways, including cell proliferation, DNA damage response and apoptosis. We aimed to assess the role of genetic variation in core circadian rhythm genes with the risk of fatal prostate cancer and morning void urinary 6-sulfatoxymelatonin levels.
Methods
We used unconditional logistic regression to evaluate the association of 96 single-nucleotide polymorphisms (SNPs) across twelve circadian-related genes with fatal prostate cancer in the AGES-Reykjavik cohort (n=24 cases), the Health Professionals Follow-Up Study (HPFS) (n=40 cases), and the Physicians’ Health Study (PHS) (n=105 cases). We used linear regression to evaluate the association between SNPs and morning void urinary 6-sulfatoxymelatonin levels in AGES-Reykjavik. We used a kernel machine test to evaluate whether multimarker SNP-sets in the pathway (gene based) were associated with our outcomes.
Results
None of the individual SNPs were consistently associated with fatal prostate cancer across the three cohorts. In each cohort, gene-based analyses showed that variation in the CRY1 gene was nominally associated with fatal prostate cancer (p-values = 0.01, 0.01, 0.05 for AGES-Reykjavik, HPFS, and PHS, respectively). In AGES-Reykjavik, SNPS in TIMELESS (4 SNPs), NPAS2 (6 SNPs), PER3 (2 SNPs) and CSNK1E (1 SNP) were nominally associated with 6-sulfatoxymelatonin levels.
Conclusion
We did not find a strong and consistent association between variation in core circadian clock genes and fatal prostate cancer risk, but observed nominally significant gene-based associations with fatal prostate cancer and 6-sulfatoxymelatonin levels.
doi:10.1007/s10552-014-0478-z
PMCID: PMC4282953  PMID: 25388799
Circadian genes; prostate cancer; genetic polymorphisms
13.  Total antioxidant intake in relation to prostate cancer incidence in the Health Professionals Follow up Study 
Epidemiologic evidence on the association of antioxidant intake and prostate cancer incidence is inconsistent. Total antioxidant intake and prostate cancer incidence has not previously been examined. Using the ferric reducing antioxidant potential (FRAP) assay, the total antioxidant content (TAC) of diet and supplements were assessed in relation to prostate cancer incidence. A prospective cohort of 47,896 men aged 40-75 years was followed from 1986 to 2008 for prostate cancer incidence (N=5,656), and they completed food frequency questionnaires (FFQ) every 4 years. A FRAP value was assigned to each item in the FFQ, and for each individual, TAC scores for diet, supplements and both (total) were calculated. Major contributors of TAC intake at baseline were: coffee (28%), fruit and vegetables (23%) and dietary supplements (23%). In multivariate analyses for dietary TAC a weak inverse association was observed; (highest versus lowest quintiles: 0.91 (0.83-1.00, p-trend=0.03) for total prostate cancer, 0.81 (0.64-1.01, p-trend=0.04) for advanced prostate cancer); this association was mainly due to coffee. No association of total TAC on prostate cancer incidence was observed. A positive association with lethal and advanced prostate cancer was observed in the highest quintile of supplemental TAC intake: 1.28 (0.98-1.65, p-trend<0.01) and 1.15 (0.92-1.43), p-trend=0.04). The weak association between dietary antioxidant intake and reduced prostate cancer incidence may be related to specific antioxidants in coffee, to non-antioxidant coffee compounds, or other effects of drinking coffee. The indication of increased risk for lethal and advanced prostate cancer with high TAC intake from supplements warrants further investigation.
doi:10.1002/ijc.28438
PMCID: PMC4274735  PMID: 23959920
Prostate cancer; Antioxidants; Oxidative stress; Diet; Risk factors
14.  Modification of the Association Between Obesity and Lethal Prostate Cancer by TMPRSS2:ERG  
Background
TMPRSS2:ERG is a hormonally regulated gene fusion present in about half of prostate tumors. We investigated whether obesity, which deregulates several hormonal pathways, interacts with TMPRSS2:ERG to impact prostate cancer outcomes.
Methods
The study included 1243 participants in the prospective Physicians’ Health Study and Health Professionals Follow-Up Study diagnosed with prostate cancer between 1982 and 2005. ERG overexpression (a TMPRSS2:ERG marker) was assessed by immunohistochemistry of tumor tissue from radical prostatectomy or transurethral resection of the prostate. Body mass index (BMI) and waist circumference, measured on average 1.3 years and 5.3 years before diagnosis, respectively, were available from questionnaires. Data on BMI at baseline was also available. We used Cox regression to calculate hazard ratios and 95% confidence intervals (CIs). All statistical tests were two-sided.
Results
During a mean follow-up of 12.8 years, 119 men developed lethal disease (distant metastases or prostate cancer death). Among men with ERG-positive tumors, the multivariable hazard ratio for lethal prostate cancer was 1.48 (95% CI = 0.98 to 2.23) per 5-unit increase in BMI before diagnosis, 2.51 (95% CI = 1.26 to 4.99) per 8-inch increase in waist circumference before diagnosis, and 2.22 (95% CI = 1.35 to 3.63) per 5-unit increase in BMI at baseline. The corresponding hazard ratios among men with ERG-negative tumors were 1.10 (95% CI = 0.76 to1.59; P interaction = .24), 1.14 (95% CI = 0.62 to 2.10; P interaction = .09), and 0.78 (95% CI = 0.52 to 1.19; P interaction = .001).
Conclusions
These results suggest that obesity is linked with poorer prostate cancer prognosis primarily in men with tumors harboring the gene fusion TMPRSS2:ERG.
doi:10.1093/jnci/djt332
PMCID: PMC3866157  PMID: 24292212
15.  Prostate-specific membrane antigen protein expression in tumor tissue and risk of lethal prostate cancer 
Background
Over-expression of prostate-specific membrane antigen (PSMA) in tumor tissue and serum has been linked to increased risk of biochemical recurrence in surgically treated prostate cancer patients, but no studies have assessed its association with disease-specific mortality.
Methods
We examined whether high PSMA protein expression in prostate tumor tissue was associated with lethal disease, and with tumor biomarkers of progression, among participants of two US-based cohorts (n=902, diagnosed 1983–2004). We used Cox proportional hazards regression to calculate multivariable hazard ratios (HR) and 95% confidence intervals (CI) of lethal prostate cancer, defined as disease-specific death or development of distant metastases (n=95). Partial Spearman rank correlation coefficients were used to correlate PSMA with tumor biomarkers.
Results
During an average 13 years of follow-up, higher PSMA expression at prostatectomy was significantly associated with lethal prostate cancer (age-adjusted HRQuartile(Q)4vs.Q1=2.42; p-trend<0.01). This association was attenuated and non-significant (multivariable-adjusted HRQ4vs.Q1=1.01; p-trend=0.52) after further adjusting for Gleason score and PSA at diagnosis. High PSMA expression was significantly (p<0.05) correlated with higher Gleason score and PSA at diagnosis, increased tumor angiogenesis, lower vitamin D receptor and androgen receptor expression, and absence of ERG expression.
Conclusions
High tumor PSMA expression was not an independent predictor of lethal prostate cancer in the current study. PSMA expression likely captures, in part, malignant features of Gleason grade and tumor angiogenesis.
Impact
PSMA is not a strong candidate biomarker for predicting prostate cancer-specific mortality in surgically treated patients.
doi:10.1158/1055-9965.EPI-13-0668
PMCID: PMC3893763  PMID: 24130224
prostate-specific membrane antigen; prostate cancer; tumor biomarkers; prognosis; angiogenesis
16.  Protein expression of PTEN, insulin-like growth factor I receptor (IGF1R), and lethal prostate cancer: a prospective study 
Background
Loss of PTEN has been shown to be associated with aggressive behavior of prostate cancer. It is less clear that loss of PTEN also increases the risk of cancer mortality. We investigated the association between PTEN expression and prostate cancer mortality, and the potential effect modification by IGF1R, a direct activator of the PI3K pathway.
Methods
Protein expression in tumor were evaluated using tumor tissues obtained from 805 participants of the Physicians’ Health and the Health Professionals Follow-up studies who were diagnosed with prostate cancer and underwent radical prostatectomy. Proportional hazard models were used to assess PTEN expression, and its interaction with IGF1R, in relation to lethal prostate cancer (cancer-specific death or distant metastases).
Results
Low PTEN expression was associated with an increase risk of lethal prostate cancer (HR = 1.7, 95% CI: 0.98-3.2, P for trend = 0.04). The association was attenuated after adjustment for Gleason grade, tumor stage, and PSA at diagnosis. A significant negative interaction between PTEN and IGF1R was found (P for interaction = 0.03). Either reduction in PTEN or increase in IGF1R expression was sufficient to worsen prognosis. Models including PTEN and IGF1R expression offer additional predicting power to prostate cancer survival, comparing to those only including demographic and clinical factors.
Conclusions
Low PTEN protein expression significantly increases the risk of lethal prostate cancer, particularly when the IGF1R expression remains at normal level.
Impact
PTEN and IGF1R expression in tumor are promising candidates for independent prognostic factors to predict lethal prostate cancer.
doi:10.1158/1055-9965.EPI-13-0349
PMCID: PMC3818474  PMID: 23983239
Prostate cancer; PTEN; Tumor biomarker; Survival; Interaction
17.  Blood Levels of Saturated and Monounsaturated Fatty Acids as Markers of De Novo Lipogenesis and Risk of Prostate Cancer 
American Journal of Epidemiology  2013;178(8):1246-1255.
De novo lipogenesis has been implicated in prostate carcinogenesis, and blood levels of specific saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) could reflect activity of this pathway. We used gas chromatography to measure blood SFA and MUFA levels in prediagnostic samples from 476 incident prostate cancer cases (1982–1995) in the Physicians' Health Study and an equal number of controls matched on age and smoking status. Five tagging polymorphisms in the fatty acid synthase (FASN) gene (rs1127678, rs6502051, rs4246444, rs12949488, and rs8066956) were related to blood SFA and MUFA levels. Conditional logistic regression was used to estimate the rate ratios, with 95% confidence intervals, of prostate cancer across quintiles of blood fatty acid levels. The polymorphisms rs6502051 and rs4246444 were associated with lower levels of 14:1n-5, 16:1n-7, and 18:1n-9. Blood levels of 16:1n-7 were associated with higher prostate cancer incidence, with rate ratios for men in increasing quintiles of 1.00, 1.40, 1.35, 1.44, and 1.97 (95% confidence interval: 1.27–3.06; Ptrend = 0.003). Furthermore, 16:1n-7 levels were positively related to incidence of high-grade (Gleason score ≥7) tumors (rate ratioQ5–Q1 = 3.92; 95% confidence interval: 1.72–8.94) but not low-grade tumors (rate ratioQ5–Q1 = 1.51; 95% confidence interval: 0.87–2.62) (Pheterogeneity = 0.02). Higher activity of enzymes involved in de novo lipogenesis, as reflected in blood levels of 16:1n-7, could be involved in the development of high-grade prostate cancer.
doi:10.1093/aje/kwt136
PMCID: PMC3792734  PMID: 23989197
biomarkers; epidemiology; fatty acids; nutrition; prostate cancer
18.  Prostate Cancer Cell Telomere Length Variability and Stromal Cell Telomere Length as Prognostic Markers for Metastasis and Death 
Cancer discovery  2013;3(10):1130-1141.
Current prognostic indicators are imperfect predictors of outcome in men with clinicallylocalized prostate cancer. Thus, tissue-based markers are urgently needed to improve treatment and surveillance decision-making. Given that shortened telomeres enhance chromosomal instability and such instability is a hallmark of metastatic lesions, we hypothesized that alterations in telomere length in the primary cancer would predict risk of progression to metastasis and prostate cancer death. To test this hypothesis, we conducted a prospective cohort study of 596 surgically treated men who participated in the ongoing Health Professionals Follow-up Study. Men who had the combination of more variable telomere length among prostate cancer cells (cell-to-cell) and shorter telomere length in prostate cancer-associated stromal cells were substantially more likely to progress to metastasis or die of their prostate cancer. These findings point to the translational potential of this telomere biomarker for prognostication and risk stratification for individualized therapeutic and surveillance strategies.
doi:10.1158/2159-8290.CD-13-0135
PMCID: PMC3797255  PMID: 23779129
Telomere; prostate cancer; prognostic marker
19.  Circulating Fatty Acids and Prostate Cancer Risk: Individual Participant Meta-Analysis of Prospective Studies 
Background
Individual studies have suggested that some circulating fatty acids are associated with prostate cancer risk, but have not been large enough to provide precise estimates of associations, particularly by stage and grade of disease.
Methods
Principal investigators of prospective studies on circulating fatty acids and prostate cancer were invited to collaborate. Investigators provided individual participant data on circulating fatty acids (weight percent) and other characteristics of prostate cancer cases and controls. Prostate cancer risk by study-specific fifths of 14 fatty acids was estimated using multivariable-adjusted conditional logistic regression. All statistical tests were two-sided.
Results
Five thousand and ninety-eight case patients and 6649 control patients from seven studies with an average follow-up of 5.1 (SD = 3.3) years were included. Stearic acid (18:0) was inversely associated with total prostate cancer (odds ratio [OR] Q5 vs Q1 = 0.88, 95% confidence interval [CI] = 0.78 to 1.00, P trend = .043). Prostate cancer risk was, respectively, 14% and 16% greater in the highest fifth of eicosapentaenoic acid (20:5n-3) (OR = 1.14, 95% CI = 1.01 to 1.29, P trend = .001) and docosapentaenoic acid (22:5n-3) (OR = 1.16, 95% CI = 1.02 to 1.33, P trend = .003), but in each case there was heterogeneity between studies (P = .022 and P < .001, respectively). There was heterogeneity in the association between docosapentaenoic acid and prostate cancer by grade of disease (P = .006); the association was statistically significant for low-grade disease but not high-grade disease. The remaining 11 fatty acids were not statistically associated with total prostate cancer risk.
Conclusion
There was no strong evidence that circulating fatty acids are important predictors of prostate cancer risk. It is not clear whether the modest associations of stearic, eicosapentaenoic, and docosapentaenoic acid are causal.
doi:10.1093/jnci/dju240
PMCID: PMC4188122  PMID: 25210201
20.  Gleason Grade Progression Is Uncommon 
Cancer research  2013;73(16):5163-5168.
Gleason grade is universally used for pathologic scoring the differentiation of prostate cancer. However, it is unknown whether prostate tumors arise well-differentiated and then progress to less differentiated forms or if Gleason grade is an early and largely unchanging feature. Prostate Specific Antigen (PSA) screening has reduced the proportion of tumors diagnosed at advanced stage, which allows assessment of this question on a population level. If Gleason grade progresses as stage does, one would expect a similar reduction in high grade tumors. We studied 1,207 Physicians’ Health Study and Health Professionals Follow-up Study participants diagnosed with prostate cancer 1982–2004 and treated with prostatectomy. We compared the distribution of grade and clinical stage across the pre-PSA and PSA screening eras. We re-reviewed grade using the ISUP 2005 revised criteria. The proportion of advanced stage tumors dropped more than six-fold, from the earliest period (12/1982–1/1993), 19.9% stage ≥T3, to the latest (5/2000–12/2004), 3% stage T3, none T4. The proportion of Gleason score ≥8 decreased substantially less, from 25.3% to 17.6%. A significant interaction between stage and diagnosis date predicting grade (p=0.04) suggests the relationship between grade and stage varies by time period. As the dramatic shift in stage since the introduction of PSA screening was accompanied by a more modest shift in Gleason grade, these findings suggest grade may be established early in tumor pathogenesis. This has implications for the understanding of tumor progression and prognosis, and may help patients diagnosed with lower grade disease feel more comfortable choosing active surveillance.
doi:10.1158/0008-5472.CAN-13-0427
PMCID: PMC3775342  PMID: 23946472
prostate cancer; Gleason score; dedifferentiation
21.  5α-reductase Inhibitors and Risk of High-grade or Lethal Prostate Cancer 
JAMA internal medicine  2014;174(8):1301-1307.
Importance
5α-reductase inhibitors (5ARIs) are widely used for benign prostatic hyperplasia despite controversy regarding potential risk of high-grade prostate cancer with use. Furthermore, the effect of 5ARIs on progression and prostate cancer death remains unclear.
Objective
To determine the association between 5ARI use and development of high-grade or lethal prostate cancer.
Design, Setting, and Participants
Prospective observational study of 38,058 men followed for prostate cancer diagnosis and outcomes between 1996–2010 in the Health Professionals Follow-up Study.
Exposure
Use of 5ARIs between 1996–2010.
Main Outcome Measures
Cox proportional hazards models were used to estimate risk of prostate cancer diagnosis or development of lethal disease with 5ARI use, adjusting for possible confounders including prostate specific antigen testing.
Results
During 448,803 person-years of follow-up, we ascertained 3681 incident prostate cancer cases. Of these, 289 were lethal (metastatic or fatal), 456 were high-grade (Gleason 8–10), 1238 were Gleason grade 7, and 1600 were low-grade (Gleason 2–6). A total of 2878 (7.6%) men reported use of 5ARIs between 1996 and 2010. After adjusting for confounders, men who reported ever using 5ARIs over the study period had a reduced risk of overall prostate cancer (HR 0.77; 95% CI, 0.65–0.91). 5ARI users had a reduced risk of Gleason 7 (HR 0.67; 95% CI, 0.49–0.91) and low-grade (Gleason 2–6) prostate cancer (HR 0.74; 95% CI, 0.57–0.95). 5ARI use was not associated with risk of high-grade (Gleason 8–10, HR 0.97; 95% CI, 0.64–1.46) or lethal disease (HR 0.99; 95% CI, 0.58–1.69). Increased duration of use was associated with significantly lower risk of overall prostate cancer (HR for 1 year of additional use 0.95; 95% CI, 0.92–0.99), localized (HR 0.95; 95% CI, 0.90–1.00), and low-grade disease (HR 0.92; 95% CI, 0.85–0.99). There was no association for lethal, high-grade, or grade 7 disease.
Conclusions and Relevance
While 5ARI use was not associated with developing high-grade or lethal prostate cancer, they were associated with a reduction in low-grade, Gleason 7 and overall prostate cancer. Since the number of patients with high-grade or lethal prostate cancer in our cohort was limited, we cannot rule out potential risk of harm with 5ARI use.
doi:10.1001/jamainternmed.2014.1600
PMCID: PMC4122627  PMID: 24887392
22.  Coffee consumption and the risk of overall and fatal prostate cancer in the NIH-AARP Diet and Health study 
Cancer causes & control : CCC  2013;24(8):1527-1534.
Purpose
Evidence on the association between coffee consumption and prostate cancer risk is inconsistent; furthermore, few studies have examined the relationship between coffee consumption and fatal prostate cancer. The aim of this study was to investigate whether coffee intake is associated with the risk of overall and fatal prostate cancer.
Methods
We conducted a prospective analysis among 288,391 men in the National Institutes of Health (NIH)-AARP Diet and Health Study who were between 50–71 years old at baseline in 1995–96. Coffee consumption was assessed at baseline. Cox proportional hazards models were used to calculate the age- and multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI).
Results
Over 11 years of follow-up, 23,335 cases of prostate cancer were ascertained, including 2,927 advanced and 917 fatal cases. Coffee consumption was not significantly associated with prostate cancer risk. The multivariable-adjusted HRs (95% CI), comparing those who drank six or more cups per day to non-drinker were; 0.94 (0.86–1.02), p-trend=0.08 for overall prostate cancer, 1.13 (0.91–1.40), p-trend=0.62 for advanced prostate cancer and 0.79 (0.53–1.17), p-trend=0.20 for fatal prostate cancer. The findings remained nonsignificant when we stratified by prostate specific antigen (PSA) testing history or restricted to non-smokers.
Conclusions
We found no statistically significant association between coffee consumption and the risk of overall, advanced or fatal prostate cancer in this cohort, though a modest reduction in risk could not be excluded.
doi:10.1007/s10552-013-0229-6
PMCID: PMC3717413  PMID: 23681472
Coffee; caffeine; prostatic neoplasms; prospective studies
23.  Renal Function Following Three Distinct Weight Loss Dietary Strategies During 2 Years of a Randomized Controlled Trial 
Diabetes Care  2013;36(8):2225-2232.
OBJECTIVE
This study addressed the long-term effect of various diets, particularly low-carbohydrate high-protein, on renal function on participants with or without type 2 diabetes.
RESEARCH DESIGN AND METHODS
In the 2-year Dietary Intervention Randomized Controlled Trial (DIRECT), 318 participants (age, 51 years; 86% men; BMI, 31 kg/m2; mean estimated glomerular filtration rate [eGFR], 70.5 mL/min/1.73 m2; mean urine microalbumin-to-creatinine ratio, 12:12) with serum creatinine <176 μmol/L (eGFR ≥30 mL/min/1.73 m2) were randomized to low-fat, Mediterranean, or low-carbohydrate diets. The 2-year compliance was 85%, and the proportion of protein intake significantly increased to 22% of energy only in the low-carbohydrate diet (P < 0.05 vs. low-fat and Mediterranean). We examined changes in urinary microalbumin and eGFR, estimated by Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration formulas.
RESULTS
Significant (P < 0.05 within groups) improvements in eGFR were achieved in low-carbohydrate (+5.3% [95% CI 2.1–8.5]), Mediterranean (+5.2% [3.0–7.4]), and low-fat diets (+4.0% [0.9–7.1]) with similar magnitude (P > 0.05) across diet groups. The increased eGFR was at least as prominent in participants with (+6.7%) or without (+4.5%) type 2 diabetes or those with lower baseline renal function of eGFR <60 mL/min/1.73 m2 (+7.1%) versus eGFR ≥60 mL/min/1.73 m2 (+3.7%). In a multivariable model adjusted for age, sex, diet group, type 2 diabetes, use of ACE inhibitors, 2-year weight loss, and change in protein intake (confounders and univariate predictors), only a decrease in fasting insulin (β = −0.211; P = 0.004) and systolic blood pressure (β = −0.25; P < 0.001) were independently associated with increased eGFR. The urine microalbumin-to-creatinine ratio improved similarly across the diets, particularly among participants with baseline sex-adjusted microalbuminuria, with a mean change of −24.8 (P < 0.05).
CONCLUSIONS
A low-carbohydrate diet is as safe as Mediterranean or low-fat diets in preserving/improving renal function among moderately obese participants with or without type 2 diabetes, with baseline serum creatinine <176 μmol/L. Potential improvement is likely to be mediated by weight loss–induced improvements in insulin sensitivity and blood pressure.
doi:10.2337/dc12-1846
PMCID: PMC3714527  PMID: 23690533
24.  Fat intake after diagnosis and risk of lethal prostate cancer and all-cause mortality 
JAMA internal medicine  2013;173(14):1318-1326.
Importance
Nearly 2.5 million men currently live with prostate cancer in the United States, yet little is known about diet after diagnosis and prostate cancer progression and overall mortality.
Objective
Examine post-diagnostic fat intake in relation to lethal prostate cancer and all-cause mortality.
Design, Setting, Participants
Prospective study of 4577 men with non-metastatic prostate cancer in the Health Professionals Follow-up Study (1986–2010).
Exposures
Post-diagnostic saturated, monounsaturated, polyunsaturated, trans, animal, and vegetable fat intakes.
Outcomes
Lethal prostate cancer (distant metastases or prostate cancer-specific death) and all-cause mortality.
Results
We observed 315 events of lethal prostate cancer and 1064 deaths (median follow-up = 8.4 y). Crude rates per 1000 person-years for lethal prostate cancer were (highest v. lowest quintile): 7.6 v. 7.3 for saturated, 6.4 v. 7.2 for monounsaturated, 5.8 v. 8.2 for polyunsaturated, 8.7 v. 6.1 for trans, 8.3 v. 5.7 for animal, and 4.7 vs. 8.7 for vegetable fat. For all-cause mortality, the rates were: 28.4 v. 21.4 for saturated, 20.0 v. 23.7 for monounsaturated, 17.1 v. 29.4 for polyunsaturated, 32.4 v. 17.1 for trans, 32.0 v. 17.2 for animal, and 15.4 v. 32.7 for vegetable fat. Post-diagnostic vegetable fat was associated with lower risk of lethal prostate cancer [hazard ratio (HR; 10% energy): 0.71; 95%CI: 0.51, 0.98; p: 0.04] and all-cause mortality [HR (10% energy): 0.74; 95%CI: 0.61, 0.88; p: 0.001]. No other fats were associated with lethal prostate cancer. Saturated and trans fats after diagnosis were associated with higher all-cause mortality [HR (5% energy): 1.30; 95% CI: 1.05, 1.60; p: 0.02 and HR (1% energy): 1.25; 95% CI: 1.05, 1.49; p: 0.01, respectively].
Conclusions
Among men with non-metastatic prostate cancer, replacing carbohydrate and animal fat with vegetable fat may reduce risk of all-cause mortality. The potential benefit of vegetable fat for prostate cancer-specific outcomes merits further research.
doi:10.1001/jamainternmed.2013.6536
PMCID: PMC3935610  PMID: 23752662
25.  Hyperglycemia, Insulin Resistance, Impaired Pancreatic β-Cell Function, and Risk of Pancreatic Cancer 
Background
Obesity and diabetes mellitus are associated with an increased risk of pancreatic cancer. These associations may be secondary to consequences of peripheral insulin resistance, pancreatic β-cell dysfunction, or hyperglycemia itself. Hemoglobin A1c (HbA1c) is a measure of hyperglycemia, whereas plasma insulin and proinsulin are markers of peripheral insulin resistance, and the proinsulin to insulin ratio marks pancreatic β-cell dysfunction.
Methods
This was a prospective, nested case-control study of 449 case patients and 982 control subjects with prediagnostic blood samples and no diabetes history from five prospective US cohorts followed through 2008. Two or three control subjects were matched to each case patient by year of birth, cohort, smoking, and fasting status. Pancreatic cancer risk was assessed by prediagnostic HbA1c, insulin, proinsulin, and proinsulin to insulin ratio with multivariable-adjusted logistic regression. All P values were two-sided.
Results
The highest vs lowest quintiles of HbA1c, insulin, and proinsulin were associated with with an increased risk for pancreatic cancer (odds ratio [OR] = 1.79; 95% confidence interval [CI] = 1.17 to 2.72, P trend = .04 for HbA1c; OR = 1.57; 95% CI = 1.08 to 2.30; Ptrend = .002 for insulin; and OR = 2.22; 95% CI = 1.50 to 3.29; P trend < .001 for proinsulin). Proinsulin to insulin ratio was not associated with pancreatic cancer risk. Results were similar across studies (all P heterogeneity > .29). In cancers developing 10 or more years after blood collection, the associations with insulin and proinsulin became stronger (highest vs lowest quintile, OR = 2.77; 95% CI = 1.28 to 5.99 for insulin and OR = 3.60; 95% CI = 1.68 to 7.72 for proinsulin). In mutually adjusted models including HbA1c, insulin, and proinsulin, only proinsulin remained statistically significant ( highest vs lowest quintile, OR = 2.55; 95% CI = 1.54 to 4.21; Ptrend < .001).
Conclusions
Among participants from five large prospective cohorts, circulating markers of peripheral insulin resistance, rather than hyperglycemia or pancreatic β-cell dysfunction, were independently associated with pancreatic cancer risk.
doi:10.1093/jnci/djt123
PMCID: PMC3714020  PMID: 23847240

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