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1.  High Prevalence of Screen Detected Prostate Cancer in West Africans: Implications for Racial Disparity of Prostate Cancer 
The Journal of urology  2014;192(3):730-735.
To our knowledge the reasons for the high rates of prostate cancer in black American men are unknown. Genetic and lifestyle factors have been implicated. Better understanding of prostate cancer rates in West African men would help clarify why black American men have such high rates since the groups share genetic ancestry and yet have different lifestyles and screening practices. To estimate the prostate cancer burden in West African men we performed a population based screening study with biopsy confirmation in Ghana.
Materials and Methods
We randomly selected 1,037 healthy men 50 to 74 years old from Accra, Ghana for prostate cancer screening with prostate specific antigen testing and digital rectal examination. Men with a positive screen result (positive digital rectal examination or prostate specific antigen greater than 2.5 ng/ml) underwent transrectal ultrasound guided biopsies.
Of the 1,037 men 154 (14.9%) had a positive digital rectal examination and 272 (26.2%) had prostate specific antigen greater than 2.5 ng/ml, including 166 with prostate specific antigen greater than 4.0 ng/ml. A total of 352 men (33.9%) had a positive screen by prostate specific antigen or digital rectal examination and 307 (87%) underwent biopsy. Of these men 73 were confirmed to have prostate cancer, yielding a 7.0% screen detected prostate cancer prevalence (65 patients), including 5.8% with prostate specific antigen greater than 4.0 ng/ml.
In this relatively unscreened population in Africa the screen detected prostate cancer prevalence is high, suggesting a possible role of genetics in prostate cancer etiology and the disparity in prostate cancer risk between black and white American men. Further studies are needed to confirm the high prostate cancer burden in African men and the role of genetics in prostate cancer etiology.
PMCID: PMC4332806  PMID: 24747091
prostatic neoplasms; prostate-specific antigen; mass screening; African Americans; Africa
2.  Non-Steroidal Anti-Inflammatory Drugs Use Is Associated with Reduced Risk of Inflammation-Associated Cancers: NIH-AARP Study 
PLoS ONE  2014;9(12):e114633.
Chronic inflammation has been linked to cancers, and use of non-steroidal anti-inflammatory drugs (NSAIDs) has been associated with reduced risk of several cancers. To further refine the magnitude of NSAID-related associations, in particular for cancers related to inflammation, such as alcohol-, infection-, obesity-, and smoking-related cancers, as well as for less common cancers, we evaluated the use of NSAIDs and cancer risk in a very large cohort. We used propensity scores to account for potential selection bias and hypothesized that NSAID use is associated with decreased cancer incidence.
We conducted a prospective study among 314,522 participants in the NIH-AARP Diet and Health Study. Individuals who completed the lifestyle questionnaire, which included NSAID use, in 1996–1997 were followed through 2006. Information on cancer incidence was ascertained by linking to cancer registries and vital status databases.
During 2,715,994 person-years of follow-up (median 10.1 person-years), there were 51,894 incident cancers. Compared with non-users of NSAIDs, individuals who reported use in the 12 months prior to interview had a significantly lower risk of all inflammation-related cancer, alcohol-related, infection-related, obesity-related, and smoking-related cancers [hazard ratio (HR) (95% CI)) 0.90 (0.87–0.93), 0.80 (0.74–0.85), 0.82 (0.78–0.87), 0.88 (0.84–0.92), and 0.88 (0.85–0.92) respectively)].
After accounting for potential selection bias, our data showed an inverse association between NSAID use and alcohol-related, infection-related, obesity-related, and smoking-related cancers and support the hypothesis that inflammation is related to an increased risk of certain cancers.
PMCID: PMC4281259  PMID: 25551641
3.  Biliary tract cancer incidence in the United States- demographic and temporal variations by anatomic site 
We evaluated incidence patterns of biliary tract cancers (gallbladder, extrahepatic bile duct, ampulla of Vater, and not otherwise specified) to provide potential insight into the etiology of these cancers. Data were obtained from the population-based Surveillance, Epidemiology, and End Results (SEER) program. Rates for cases diagnosed during 1992–2009 were calculated by racial/ethnic, gender, and age groups. Temporal trends during 1974–2009 and annual percentage changes (APC) during 1992–2009 were estimated. Age-adjusted rates by site were higher among American Indian/Alaska Natives, Hispanics (white) and Asian/Pacific Islanders (Asian/PI) and lower among whites and blacks. Gallbladder cancer was more common among women in all ethnic groups (female-to-male incidence rate ratio [IRR] ranged from 1.24 to 2.86), but bile duct and ampulla of Vater cancers were more common among men (female-to-male IRR 0.57 to 0.82). Gallbladder cancer rates declined among all racial/ethnic and gender groups except blacks (APC −0.4% to −3.9%). In contrast, extrahepatic bile duct cancer rates rose significantly in most female racial/ethnic groups; the APCs among whites were 0.8 among females and 1.3 among males, both significant. Rates for ampulla of Vater cancer decreased among Asian/PI females (APC −2.7%) but remained stable for the other groups. In addition to confirming that biliary tract cancer incidence patterns differ by gender and site, and that the gallbladder cancer incidence rates have been declining, this study provides novel evidence that extrahepatic bile duct cancer rates are rising. These observations may help guide future etiologic studies.
PMCID: PMC3713194  PMID: 23504585
biliary tract cancer; gallbladder cancer; extrahepatic bile duct cancer; ampulla of Vater cancer; Klatskin tumors; incidence
4.  Prospective evaluation of serum sarcosine and risk of prostate cancer in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial 
Carcinogenesis  2013;34(10):2281-2285.
Metabolomic profiling has identified, sarcosine, a derivative of the amino acid glycine, as an important metabolite involved in the etiology or natural history of prostate cancer. We examined the association between serum sarcosine levels and risk of prostate cancer in 1122 cases (813 non-aggressive and 309 aggressive) and 1112 controls in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Sarcosine was quantified using high-throughput liquid chromatography–mass spectrometry. A significantly increased risk of prostate cancer was observed with increasing levels of sarcosine (odds ratio [OR] for the highest quartile of exposure [Q4] versus the lowest quartile [Q1] = 1.30, 95% confidence interval [CI]: 1.02, 1.65; P-trend 0.03). When stratified by disease aggressiveness, we observed a stronger association for non-aggressive cases (OR for Q4 versus Q1 = 1.44, 95% CI: 1.11, 1.88; P-trend 0.006) but no association for aggressive prostate cancer (OR for Q4 versus Q1 = 1.03, 95% CI: 0.73, 1.47; P-trend 0.89). Although not statistically significant, temporal analyses showed a stronger association between sarcosine and prostate cancer for serum collected closer to diagnosis, suggesting that sarcosine may be an early biomarker of disease. Interestingly, the association between sarcosine and prostate cancer risk was stronger among men with diabetes (OR = 2.66, 95% CI: 1.04, 6.84) compared with those without reported diabetes (OR = 1.23, 95% CI: 0.95–1.59, P-interaction = 0.01). This study found that elevated levels of serum sarcosine are associated with an increased prostate cancer risk and evidence to suggest that sarcosine may be an early biomarker for this disease.
PMCID: PMC3786375  PMID: 23698636
5.  Variants in CCK and CCKAR genes to susceptibility to biliary tract cancers and stones: a population-based study in Shanghai, China 
Journal of gastroenterology and hepatology  2013;28(9):10.1111/jgh.12278.
Background and Aim
Altered motility of the gallbladder is associated with an increased risk of gallstones and can result in biliary tract cancers. Cholecystokinin (CCK) is an important modulator of gallbladder motility which functions by activating CCK type-A receptor (CCKAR). The aim of this study was to determine whether genetic variants in CCK and CCKAR are associated with the risk of biliary tract cancers and stones.
We investigated the associations between 9 single nucleotide polymorphisms (SNPs) in CCK and CCKAR in a population-based case-control study, including 439 biliary tract cancer cases (253 gallbladder, 133 extrahepatic bile duct and 53 ampulla of Vater cancer cases), 429 biliary stone cases, and 447 population controls in Shanghai, China.
We found that women with the CCKAR rs1800855 AA genotype had an increased risk of gallbladder cancer (odd ratio (OR) =2.37, 95% confidence interval (CI): 1.36–4.14) compared to subjects with the TT genotype, and remained significant after Bonferroni correction (P=0.0056). Additionally, female carriers of the CCKAR haplotype C-T-C-T (rs2071011-rs915889-rs3822222-rs1800855) had a reduced risk of gallbladder cancer (OR=0.61, 95%CI: 0.43–0.86) compared to those with the G-C-C-A haplotype, the association also remained significant after Bonferroni correction.
These findings suggest that variants in the CCKAR gene may influence the risk of gallbladder cancer in women. Additional studies are needed to confirm our findings.
PMCID: PMC3820582  PMID: 23701593
biliary tract cancer; gallstone; CCK and CCKAR; variant; haplotype; susceptibility
6.  Body mass index and mortality among blacks and whites in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial 
Obesity (Silver Spring, Md.)  2013;22(1):260-268.
In a large prospective cohort, we examined the relationship of BMI with mortality among blacks and compared the results to those among whites in this population.
Design and methods
The study population consisted of 7,446 non-Hispanic black and 130,598 white participants, ages 49–78 at enrollment, in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. BMI at baseline, BMI at age 20, and BMI change were calculated using self-reported and recalled height and weight. Relative risks were stratified by race and sex and adjusted for age, education, marital status, and smoking.
1,495 black and 18,236 white participants died during follow-up (mean=13 years). Clear J-shaped associations between BMI and mortality were observed among white men and women. Among black men and women, the bottoms of these curves were flatter, and increasing risks of death with greater BMI were observed only at higher BMI levels (≥35.0). Associations for BMI at age 20 and BMI change also appeared to be stronger in magnitude in whites versus blacks, and these racial differences appeared to be more pronounced among women.
Our results suggest that BMI may be more weakly associated with mortality in blacks, particularly black women, than in whites.
PMCID: PMC3690173  PMID: 23512729
7.  Variants in motilin, somatostatin and their receptor genes and risk of biliary tract cancers and stones in Shanghai, China 
Meta Gene  2014;2:418-426.
Altered motility of the gallbladder can result in gallstone and cholecystitis, which are important risk factors for biliary tract cancer. Motilin (MLN) and somatostatin (SST) are known important modulators of gallbladder motility. To determine whether genetic variants in motilin, somatostatin, and their receptor genes are associated with the risk of biliary tract cancers and stones, nine tag-SNPs were determined in 439 biliary tract cancer cases (253 gallbladder, 133 extrahepatic bile duct and 53 ampulla of Vater cancer cases), 429 biliary stone cases, and 447 population controls in a population-based case–control study in Shanghai, China. We found that subjects with the MLNR rs9568169 AA genotype and SSTR5 rs169068 CC genotype were significantly associated with risk of extrahepatic bile duct cancer (OR = 0.49, 95% CI: 0.27–0.89; OR = 2.40, 95% CI: 1.13–5.13) compared to the major genotypes. MLN rs2281820 CT and rs3793079 AT genotypes had significantly increased risks of gallstones (OR = 1.52, 95% CI: 1.06–2.18; OR = 1.64, 95% CI: 1.20–2.25) compared to TT genotypes. Besides, haplotype analysis showed that MLN T-T-T haplotype (rs2281820–rs3793079–rs2281819) had a non-significantly elevated risk of gallstone (OR = 1.30, 95% CI: 0.91–1.86) compared with C-A-A haplotype. To the best of our knowledge, this is the first study to report an association between genetic polymorphisms in MLN, MLNR and their receptor genes and risk of biliary tract cancers and stones.
•We conduct a population-based case–control study of biliary tract diseases in China.•We examine nine TagSNPs in gallbladder motility genes in this study.•MLNR rs9568169 and SSTR5 rs169068 are related to extrahepatic bile duct cancer risk.•MLN rs2281820 and rs3793079 are associated with gallstone risk.
PMCID: PMC4080205  PMID: 24999450
Biliary tract cancer; Gallstone; MLN and MLNR; SSTR2 and SSTR5; Genetic susceptibility
8.  Known glioma risk loci are associated with glioma with a family history of brain tumours - a case-control gene association study 
Familial cancer can be used to leverage genetic association studies. Recent genome-wide association studies have reported independent associations between seven single nucleotide polymorphisms (SNPs) and risk of glioma. The aim of this study was to investigate whether glioma cases with a positive family history of brain tumours, defined as having at least one first or second degree relative with a history of brain tumour, are associated with known glioma risk loci. 1431 glioma cases and 2868 cancer-free controls were identified from four case-control studies and two prospective cohorts from USA, Sweden, and Denmark and genotyped for seven SNPs previously reported to be associated with glioma risk in case-control designed studies. Odds ratios were calculated by unconditional logistic regression. In analyses including glioma cases with a family history of brain tumours (n=104) and control subjects free of glioma at baseline, three out of seven SNPs were associated with glioma risk; rs2736100 (5p15.33, TERT), rs4977756 (9p21.3, CDKN2A-CDKN2B), and rs6010620 (20q13.33, RTEL1). After Bonferroni correction for multiple comparisons, only one marker was statistically significantly associated with glioma risk, rs6010620 (ORtrend for the minor (A) allele, 0.39; 95% CI, 0.25–0.61; Bonferroni adjusted ptrend, 1.7×10−4). In conclusion, as previously shown for glioma regardless of family history of brain tumours, rs6010620 (RTEL1) was associated with an increased risk of glioma when restricting to cases with family history of brain tumours. These findings require confirmation in further studies with a larger number of glioma cases with a family history of brain tumours.
PMCID: PMC3586297  PMID: 23115063
Glioma; brain tumours; genome-wide association study; single nucleotide polymorphism
9.  Metabolomics in Epidemiology: Sources of Variability in Metabolite Measurements and Implications 
Metabolite levels within an individual vary over time. This within-individual variability, coupled with technical variability, reduces the power for epidemiological studies to detect associations with disease. Here, the authors assess the variability of a large subset of metabolites and evaluate the implications for epidemiologic studies.
Using LC-MS and GC-MS platforms, 385 metabolites were measured in 60 women at baseline and year-1 of the Shanghai Physical Activity Study, and observed patterns were confirmed in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening study.
Although the authors found high technical reliability (median intra-class correlation = 0.8), reliability over time within an individual was low. Taken together, variability in the assay and variability within the individual accounted for the majority of variability for 64% of metabolites. Given this, a metabolite would need, on average, a Relative Risk of 3 (comparing upper and lower quartiles of “usual” levels) or 2 (comparing quartiles of observed levels) to be detected in 38%, 74% and 97% of studies including 500, 1000, and 5000 individuals. Age, gender, and fasting status, factors which are often of less interest in epidemiological studies were associated with 30%, 67%, and 34% of metabolites, respectively, but the associations were weak, and explained only a small proportion of the total metabolite variability.
Metabolomics will require large, but feasible, sample sizes to detect the moderate effect sizes typical for epidemiological studies.
We offer guidelines for determining the sample sizes needed to conduct metabolomic studies in epidemiology.
PMCID: PMC3617076  PMID: 23396963
metabolomics; power; variance components; measurement error
11.  Androgen Receptor CAG Repeat Length and Association with Prostate Cancer Risk: Results from the Prostate Cancer Prevention Trial 
The Journal of urology  2010;184(6):2297-2302.
We investigated the association between the length of the polymorphic trinucleotide CAG microsatellite repeats in exon 1 of the androgen receptor (AR) gene and the risk of prostate cancer.
This is a nested case-control study of 1159 cases and 1353 controls drawn from the Prostate Cancer Prevention Trial, a randomized, placebo-controlled trial testing whether finasteride, a 5α-reductase inhibitor, could reduce the 7-year period prevalence of prostate cancer. During the course of the PCPT, men underwent annual DRE and PSA measures and a prostate biopsy was recommended for all men with an abnormal DRE or a finasteride-adjusted PSA of > 4.0 ng/mL. Cases were drawn from men with biopsy-determined prostate cancer identified either by a for-cause or end-of-study biopsy and controls were selected from men who completed the end-of-study biopsy procedure.
CAG repeat mean lengths were not different between cases and controls. The frequency distribution for cases and controls for the AR CAG repeat length is similar. There were no significant associations of CAG repeat length with prostate cancer risk, either when stratified by treatment arm (finasteride or placebo) or when combined together. There was also no significant association between CAG repeat length and the risk of low- or high-grade prostate cancer.
There were no associations of the AR CAG repeat length and prostate cancer risk. Knowledge of AR CAG repeat length provides no clinical useful information for predicting prostate cancer risk.
PMCID: PMC3930175  PMID: 20952028
androgen receptor; CAG repeat length; prostate cancer
The role of the insulin-like growth factor (IGF) axis and whether IGFs interact with androgen-suppressing agents in relation to prostate carcinogenesis is unclear. This nested case-control study (n=1652 cases/1543 controls) examined whether serum IGF1, IGF2, IGFBP2, IGFBP3 and the IGF1:IGFBP3 ratio were associated with prostate cancer in the Prostate Cancer Prevention Trial, a randomized, placebo-controlled trial of finasteride for prostate cancer prevention. Presence or absence of cancer was determined by prostate biopsy. Baseline serum was assayed for IGF-axis analytes using ELISA. Logistic regression estimated odds ratios and 95% confidence intervals for risk of total, low-grade (Gleason 2–6) and high-grade (Gleason 7–10) cancers. Results were stratified by intervention assignment. In both the placebo and finasteride arms, serum IGF1, IGF2, IGFBP3 and the IGF1:IGFBP3 ratio were not associated with prostate cancer. However men in the highest vs. lowest quartile of serum IGFBP2 had a 48% (P-trend =0.02) and 55% (P-trend=0.01) increased risk for total and low-grade cancers respectively. These IGFBP2 associations were attenuated and no longer statistically significant in the finasteride arm. Our results suggest that in general, serum IGF-axis analytes were not associated with prostate cancer risk in the PCPT where presence or absence of all cancers was biopsy-determined. The exception was the finding that high serum IGFBP2 is a risk factor for low-grade disease, which was attenuated for men on finasteride. Further research is needed to understand better the risk incurred by high IGFBP2 and whether androgen-suppressing agents such as finasteride influence aspects of IGFBP2 physiology relevant to prostate carcinogenesis.
PMCID: PMC3565024  PMID: 23315596
prostate cancer; insulin-like growth factors; randomized trials; 5-α reductase inhibitors
13.  Prostate Cancer Incidence Rates in Africa 
Prostate Cancer  2011;2011:947870.
African American men have among the highest prostate cancer incidence rates in the world yet rates among their African counterparts are unclear. In this paper, we compared reported rates among black men of Sub-Saharan African descent using data from the International Agency for Research on Cancer (IARC) and the National Cancer Institute Surveillance, Epidemiology, and End Results Program for 1973–2007. Although population-based data in Africa are quite limited, the available data from IARC showed that rates among blacks were highest in the East (10.7–38.1 per 100,000 man-years, age-adjusted world standard) and lowest in the West (4.7–19.8). These rates were considerably lower than those of 80.0–195.3 observed among African Americans. Rates in Africa increased over time (1987–2002) and have been comparable to those for distant stage in African Americans. These patterns are likely due to differences between African and African American men in medical care access, screening, registry quality, genetic diversity, and Westernization. Incidence rates in Africa will likely continue to rise with improving economies and increasing Westernization, warranting the need for more high-quality population-based registration to monitor cancer incidence in Africa.
PMCID: PMC3200287  PMID: 22111004
14.  Association between genetic variants in the 8q24 cancer risk regions and circulating levels of androgens and sex-hormone binding globulin 
Genome-wide association studies have identified multiple independent regions on chromosome 8q24 that are associated with cancers of the prostate, breast, colon, and bladder.
To investigate their biological basis, we examined the possible association between 164 single nucleotide polymorphism (SNPs) in the 8q24 risk regions, spanning 128,101,433–128,828,043 bp, and serum androgen (testosterone, androstenedione, 3αdiol G, and bioavailable testosterone) and sex hormone-binding globulin levels in 563 healthy, non-Hispanic, Caucasian men (55–74 years old) from a prospective cohort study, the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Age-adjusted linear regression models were used to determine the association between the SNPs in an additive genetic model and log transformed biomarker levels.
Three adjacent SNPs centromeric to prostate cancer risk-region 2 (rs12334903, rs1456310, and rs980171) were associated with testosterone (P<1.1×10−3) and bioavailable testosterone (P<6.3×10−4). Suggestive associations were seen for a cluster of 9 SNPs in prostate cancer risk region 1 and androstenedione (P<0.05).
These preliminary findings require confirmation in larger studies, but raise the intriguing hypothesis that genetic variations in the 8q24 cancer risk regions may correlate with androgen levels.
These results may provide some clues for the strong link between 8q24 and prostate cancer risk.
PMCID: PMC2901401  PMID: 20551303
8q24; genetic polymorphisms; serum androgens
15.  Individual Variations in Serum Melatonin Levels through Time: Implications for Epidemiologic Studies 
PLoS ONE  2013;8(12):e83208.
Melatonin, a marker for the circadian rhythm with serum levels peaking between 2AM and 5AM, is hypothesized to possess anti-cancer properties, making it a mechanistic candidate for the probable carcinogenic effect of circadian rhythm disruption. In order to weigh epidemiologic evidence on the association of melatonin with cancer, we must first understand the laboratory and biological sources of variability in melatonin levels measured in samples. Participants for this methodological study were men enrolled in the Prostate Lung Colorectal and Ovarian Cancer Screening Trial (PLCO). We measured serum melatonin levels over a five year period in 97 individuals to test if melatonin levels are steady over time. The Pearson correlation coefficient between two measures separated by 1 year was 0.87, while the correlation between two measures separated by 5 years was to 0.70. In an additional cross-sectional study of 292 individuals, we used Analysis of Variance to identify differences in melatonin levels between different lifestyle and environmental characteristics. Serum melatonin levels were slightly higher in samples collected from 130 individuals during the winter, (6.36±0.59 pg/ml) than in samples collected from 119 individuals during the summer (4.83±0.62 pg/ml). Serum melatonin levels were lowest in current smokers (3.02±1.25 pg/ml, p = 0.007) compared to never (6.66±0.66 pg/ml) and former (5.59±0.50 pg/ml) smokers whereas BMI did not significantly affect serum melatonin levels in this study. In conclusion, the high 5 year correlation of melatonin levels implies that single measurements may be used to detect population level associations between melatonin and risk of cancer. Furthermore, our results reiterate the need to record season of sample collection, and individual characteristics in order to maximize study power and prevent confounding.
PMCID: PMC3871612  PMID: 24376664
16.  Association of 17 Prostate Cancer Susceptibility Loci with Prostate Cancer Risk in Chinese Men 
The Prostate  2010;70(4):425-432.
Several genome-wide association studies (GWAS) in populations of European descent have identified more than a dozen common genetic variants that are associated with prostate cancer risk.
To determine whether these variants are also associated with prostate cancer risk in the Chinese population, we evaluated 17 prostate cancer susceptibility loci in a population-based case-control study from Shanghai, including 288 prostate cancer cases and 155 population controls.
After adjusting for age, two of the 17 loci were significantly associated with prostate cancer risk, while the other 15 loci were suggestively associated with prostate cancer risk in this population. The strongest associations were found for chromosome 8q24 Region 2 (rs1016343: OR=2.07, 95% CI: 1.35-3.20, P=9.4×10-4) and 8q24 Region 1 (rs10090154: OR=2.07, 95% CI: 1.31-3.28, P=0.002); additional single nucleotide polymorphisms (SNPs) assessed in these two 8q24 regions were also significant (ORRegion2=1.92-2.05, P=9.4×10-4-0.003, and ORRegion1=1.77-1.81, P=0.01 for all SNPs).
Our study shows that multiple prostate cancer risk loci identified in European populations using GWAS are also associated with prostate cancer risk in Chinese men, a low-risk population with mostly clinically relevant cancers. Larger studies in Chinese and Asian populations are needed to confirm these findings and the role of these risk loci in prostate cancer etiology in Asian men.
PMCID: PMC3078699  PMID: 19866473
prostate cancer; association; Asian; Chinese; 8q24
17.  Measuring Serum Melatonin in Epidemiologic Studies 
Epidemiologic data on serum melatonin, a marker of circadian rhythms, and cancer are sparse due largely to the lack of reliable assays with high sensitivity to detect relatively low melatonin levels in serum collected during daylight, as commonly available in most epidemiologic studies.
To help expand epidemiologic research on melatonin, we assessed the reproducibility and refined a currently available melatonin radioimmunoassay, and evaluated its application to epidemiologic investigations by characterizing melatonin levels in serum, urine, and/or plasma in 135 men from several ethnic groups.
Reproducibility was high for the standard 1.0 ml serum- (mean coefficient of variation (CV)=6.9%, intraclass correlation coefficient (ICC)=97.4%, n=2 serum pools in triplicate) and urine-based (mean CV=3.5%, ICC=99.9%) assays. Reproducibility for the 0.5 ml refined-serum assay was equally good (mean CV=6.6%%;ICC=99.0%). There was a positive correlation between morning serum melatonin and 6-sulfatoxymelatonin in 24-hour urine(r=0.46, P=0.008; n=49 subjects). Melatonin levels in serum-plasma pairs had a high correlation (r=0.97, P<1 × 10−4; n=20) Morning serum melatonin levels were five times higher than those from the afternoon (before 9 AM mean = 11.0 pg/mL versus after 11 AM mean=2.0 pg/mL). Chinese men had lower melatonin levels (mean=3.4 pg/mL), while Caucasian, African American, and Ghanaian men had similar levels (mean=6.7–8.6 pg/mL).
These results suggest that melatonin can be detected reliably in serum samples collected in epidemiologic studies in various racial groups.
With improved assays, it may be possible to investigate the role of melatonin and the emerging circadian rhythm hypothesis in cancer etiology in epidemiologic studies.
PMCID: PMC2856692  PMID: 20332275
melatonin; radioimmunoassay; assay variation; reproducibility
18.  Finasteride modifies the relation between serum C-peptide and prostate cancer risk: results from the Prostate Cancer Prevention Trial 
Cancer prevention research (Philadelphia, Pa.)  2010;3(3):10.1158/1940-6207.CAPR-09-0188.
Hyperinsulinemia and obesity-related metabolic disturbances are common and have been associated with increased cancer risk and poor prognosis.
Data are from a case-control study within the Prostate Cancer Prevention Trial (PCPT), a randomized, placebo-controlled trial testing finasteride vs. placebo for primary prevention of prostate cancer. Cases (n=1803) and controls (n= 1797) were matched on age, PCPT treatment arm, and family history of prostate cancer; controls included all eligible non-whites. Outcomes were biopsy-determined. Baseline bloods were assayed for serum C-peptide (marker of insulin secretion) and leptin (an adipokine) using ELISA. Logistic regression calculated odds ratios for total prostate cancer and polytomous logistic regression calculated odds ratios for low-grade (Gleason < 7) and high-grade (Gleason ≥ 7) disease. Results were stratified by treatment arm for C-peptide.
For men on placebo, higher vs. lower serum C-peptide was associated with a near two-fold increased risk of high-grade prostate cancer (Gleason ≥ 7) (multivariate-adjusted OR= 1.88, 95%CI 1.19-2.97, p trend = 0.004). When C-peptide was modeled as a continuous variable, every unit increase in [log(C-peptide)], resulted in a 39% increased risk of high-grade disease (p=0.01). In contrast, there was no significant relationship between C-peptide and high-grade prostate cancer among men receiving finasteride. Leptin was not independently associated with high-grade prostate cancer.
These results support findings from other observational studies that high serum C-peptide and insulin-resistance, but not leptin, are associated with increased risk of high-grade prostate cancer. Our novel finding is that the C-peptide-associated risk was attenuated by use of finasteride.
PMCID: PMC3846551  PMID: 20179296
prostate neoplasms; finasteride; obesity; insulin; insulin resistance; C-peptide; leptin
19.  Non-steroidal anti-inflammatory drug use and the risk of benign prostatic hyperplasia-related outcomes and nocturia in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial 
BJU international  2012;110(7):1050-1059.
To investigate the relationship between non-steroidal anti-inflammatory drug (NSAID) use and the incidence of benign prostatic hyperplasia (BPH)-related outcomes and nocturia, a lower urinary tract symptom (LUTS) of BPH, in light of accumulating evidence suggesting a role for inflammation in BPH/LUTS development.
Patients and methods
At baseline, participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial completed questions on recent, regular aspirin and ibuprofen use, BPH surgery, diagnosis of an enlarged prostate/BPH, and nocturia. Participants in the intervention arm also underwent a digital rectal examination (DRE), from which prostate dimensions were estimated, as well as a prostate-specific antigen (PSA) test. Only participants in the intervention arm without BPH/LUTS at baseline were included in the analysis (n = 4771).
During follow-up, participants underwent annual DREs and PSA tests, provided annual information on finasteride use, and completed a supplemental questionnaire in 2006–2008 that included additional questions on diagnosis of an enlarged prostate/BPH and nocturia.
Information collected was used to investigate regular aspirin or ibuprofen use in relation to the incidence of six BPH/LUTS definitions: diagnosis of an enlarged prostate/BPH, nocturia (waking two or more times per night to urinate), finasteride use, any self-reported BPH/LUTS, prostate enlargement (estimated prostate volume ≥ 30 mL on any follow-up DRE) and elevation in PSA level (> 1.4 ng/mL on any follow-up PSA test).
Generally, null results were observed for any recent, regular aspirin or ibuprofen use (risk ratio = 0.92–1.21, P = 0.043–0.91) and frequency of use (risk ratio for one category increase in NSAID use = 0.98–1.11, P-trends = 0.10–0.99) with incident BPH/LUTS.
The findings obtained in the present study do not support a protective role for recent NSAID use in BPH/LUTS development.
PMCID: PMC3382045  PMID: 22429766
aspirin; benign prostatic hyperplasia; ibuprofen; lower urinary tract symptoms; non-steroidal anti-inflammatory drugs
20.  Associations of serum sex steroid hormones and 5α-androstane-3α,17β-diol glucuronide concentrations with prostate cancer risk among men treated with finasteride 
Finasteride, an inhibitor of 5 α-reductase (Type II), lowers intraprostatic dihydrotestosterone (DHT), which is reflected in serum as reduced 5α-androstane-3α,17β-diol glucuronide (3α-dG). It also modestly increases serum testosterone (T), estrone (E1) and estradiol (E2). In this altered hormonal milieu, it is unknown whether serum concentrations of these hormones are associated with prostate cancer risk.
In this nested case-control study of men in the finasteride arm of the Prostate Cancer Prevention Trial, sex steroid hormones and sex hormone binding globulin (SHBG) were measured at baseline and approximately 3-years post-treatment in 553 prostate cancer cases and 694 controls.
Median post-treatment changes in concentrations of 3α-dG, T, E1, and E2 were −73.8%, +10.1%, +11.2%, and +7.5% (all p<0.001), respectively. Neither the pre- nor post-treatment concentrations of 3α-dG, nor its change, were associated with risk. Pre-treatment, high concentrations of E1 and low concentrations of T were associated with increased cancer risk (Odds Ratio[95% CI] quartile 4 vs 1: 1.38[0.99–1.93] ptrend=0.03; 0.64 [0.43–0.93] ptrend=0.07, respectively). Post-treatment, high concentrations of both E1 and E2 and were associated with increased cancer risk (OR[95% CI] quartile 4 vs 1: 1.54[1.09–2.17] ptrend=0.03; 1.49[1.07–2.07] ptrend=0.02, respectively).
Among finasteride-treated men, concentrations of 3α-dG were not associated with total or Gleason grades 2–6, 7–10 or 8–10 cancer. High serum estrogens may increase cancer risk when intraprostatic DHT is pharmacologically lowered.
Low post-treatment serum estrogens may identify men more likely to benefit from use of finasteride to prevent prostate cancer.
PMCID: PMC3467348  PMID: 22879203
21.  Variants of DNA Repair Genes and the Risk of Biliary Tract Cancers and Stones: A population-based study in China 
Biliary tract cancers, encompassing tumors of the gallbladder, extrahepatic ducts, and ampulla of Vater, are relatively rare tumors with a high fatality rate. Other than a close link with gallstones, the etiology of biliary tract cancers is poorly understood. We conducted a population-based case-control study in Shanghai, China, to examine whether genetic variants in several DNA repair genes are associated with biliary tract cancers or biliary stones. Genomic DNA from 411 patients with biliary tract cancers (237 gallbladder, 127 bile duct, and 47 ampulla of Vater), 891 patients with biliary stones, and 786 healthy subjects randomly selected from the Shanghai population, was genotyped for 6 single nucleotide polymorphisms (SNPs) in 4 DNA repair genes (MGMT, RAD23B, CCNH, and XRCC3). Of the 6 SNPs, only one (MGMT EX5-25C>T, rs12917) was associated with biliary tract cancer. Independent of gallstones, subjects carrying the CT genotype of the MGMT EX5-25C>T marker had a significantly reduced risk of gallbladder cancer (odds ratio (OR)=0.63; 95% confidence interval (CI): 0.41-0.97; Ptrend = 0.02) and non-significant reduced risks of bile duct (OR=0.61; 95% CI: 0.35-1.06) and ampulla of Vater (OR=0.85; 95% CI: 0.39-1.87) cancers. However, this marker was not associated with biliary stones, and the other markers examined were not significantly associated with either biliary tract cancers or stones. Findings from this population-based study in Shanghai suggest that MGMT gene variants may alter susceptibility to biliary tract cancer, particularly gallbladder cancer. Confirmation in future studies, however, is required.
PMCID: PMC2860746  PMID: 18708406
Biliary tract cancers; gallbladder; extrahepatic bile duct; ampulla of Vater; DNA repair; polymorphism; China
Cancer causes & control : CCC  2012;23(9):1511-1518.
To investigate serologic evidence of infection by cytomegalovirus (CMV), a herpesvirus with known oncogenic potential that has been detected in malignant prostate tissue, in relation to prostate cancer (PCa) risk in a large case-control study nested in the Prostate Cancer Prevention Trial (PCPT).
Cases were men with a confirmed diagnosis of PCa after visit 2 (n=614) and controls were men not diagnosed with PCa during the trial who also had a negative end-of-study biopsy (n=616). Controls were frequency-matched to cases by age, treatment arm, and family history of PCa. Sera from visit 2 were tested for CMV IgG antibodies.
No association was observed between CMV serostatus and PCa risk (adjusted CMV seroprevalence=67.9% for cases and 65.2% for controls, odds ratio=1.13, 95% confidence interval: 0.89–1.45).
Considering our null findings in the context of the full CMV literature, CMV infection, as measured by serostatus, does not appear to increase PCa risk.
PMCID: PMC3433040  PMID: 22810146
Cytomegalovirus; infection; prostate cancer; epidemiology
23.  Evolution and Taxonomic Classification of Alphapapillomavirus 7 Complete Genomes: HPV18, HPV39, HPV45, HPV59, HPV68 and HPV70 
PLoS ONE  2013;8(8):e72565.
The species Alphapapillomavirus 7 (alpha-7) contains human papillomavirus genotypes that account for 15% of invasive cervical cancers and are disproportionately associated with adenocarcinoma of the cervix. Complete genome analyses enable identification and nomenclature of variant lineages and sublineages.
The URR/E6 region was sequenced to screen for novel variants of HPV18, 39, 45, 59, 68, 70, 85 and 97 from 1147 cervical samples obtained from multiple geographic regions that had previously been shown to contain an alpha-7 HPV isolate. To study viral heterogeneity, the complete 8 kb genome of 128 isolates, including 109 sequenced for this analysis, were annotated and analyzed. Viral evolution was characterized by constructing phylogenic trees using maximum-likelihood and Bayesian algorithms. Global and pairwise alignments were used to calculate total and ORF/region nucleotide differences; lineages and sublineages were assigned using an alphanumeric system. The prototype genome was assigned to the A lineage or A1 sublineage.
The genomic diversity of alpha-7 HPV types ranged from 1.1% to 6.7% nucleotide sequence differences; the extent of genome-genome pairwise intratype heterogeneity was 1.1% for HPV39, 1.3% for HPV59, 1.5% for HPV45, 1.6% for HPV70, 2.1% for HPV18, and 6.7% for HPV68. ME180 (previously a subtype of HPV68) was designated as the representative genome for HPV68 sublineage C1. Each ORF/region differed in sequence diversity, from most variable to least variable: noncoding region 1 (NCR1) / noncoding region 2 (NCR2) > upstream regulatory region (URR) > E6 / E7 > E2 / L2 > E1 / L1.
These data provide estimates of the maximum viral genomic heterogeneity of alpha-7 HPV type variants. The proposed taxonomic system facilitates the comparison of variants across epidemiological and molecular studies. Sequence diversity, geographic distribution and phylogenetic topology of this clinically important group of HPVs suggest an independent evolutionary history for each type.
PMCID: PMC3745470  PMID: 23977318
24.  High prevalence of polyclonal hypergamma-globulinemia in adult males in Ghana, Africa 
American journal of hematology  2011;86(7):554-558.
Chronic antigenic stimulation is associated with hypergamma-globulinemia. Higher rates of hypergamma-globulinemia in tropical populations are maintained even with migration to temperate regions. We conducted a population-based screening study to assess the prevalence and risk factors for hypergamma-globulinemia in Ghana, Africa. 917 Ghanaian males (50–74 years) underwent in-person interviews and health examinations. Serum from all persons was analyzed by electrophoresis performed on agarose gel; serum with a discrete/localized band was subjected to immunofixation. 54 persons with monoclonal proteins were excluded and 17 samples were insufficient for analysis. Using logistic regression and Chi-square statistics we analyzed patterns of hypergamma-globulinemia. Among 846 study subjects, the median γ-globulin level was 1.86 g/dL. On the basis of a U.S. reference, 616 (73%) had hypergamma-globulinemia (>1.6 g/dL) and 178 (21%) had γ-globulin levels >2.17 gm/dl. On multivariate analyses, lower education status (P = 0.0013) and never smoking (P = 0.038) were associated with increased γ-globulin levels. Self-reported history of syphilis was associated with hypergamma-globulinemia. We conclude that three quarters of this population-based adult Ghanaian male sample had hypergamma-globulinemia with γ-globulin levels >1.6 g/dL. Future studies are needed to uncover genetic and environmental underpinnings of our finding, and to define the relationship between hypergamma-globulinemia, monoclonal gammopathy of undetermined significance (MGUS), and multiple myeloma.
PMCID: PMC3736856  PMID: 21674575
25.  Detectability and reproducibility of plasma levels of chemokines and soluble receptors☆ 
Results in Immunology  2013;3:79-84.
Background: Multiplex assays are available to measure an array of circulating chemokines, soluble cytokine receptors and growth factors. However, there is limited information regarding whether these analytes are suitable for large-scale epidemiological studies to assess their relationships with chronic diseases, including cancer.
Methods: We examined detectability, assay repeatability, and 3-year within-subject reproducibility of plasma levels of 25 chemokines and 11 soluble receptors of cytokines and growth factors selected from the Human Millipore Panels. Plasma samples were obtained from 36 men (average age 62 years) and 17 women (average age 32 years) who participated in two epidemiological studies. Inter-assay and within-subject reproducibility were assessed by intraclass correlation coefficients (ICC).
Results: All analytes, except lymphotactin (47% detectability), were detectable in >90% of plasma samples. Inter-assay reproducibility for all analytes in 36 men tested three times on separate days were good to excellent (ICCs: 0.71–1.00). Within-subject reproducibility in 17 women sampled three times in three years were excellent (ICC ≥ 0.75) for five chemokines (eotaxin, fractalkine, 6Ckine, eotaxin 3, and SDF-1α+β) and three soluble receptors (sIL-1R2, sIL-4R and sVEGFR2); ICCs were fair to good (0.4 ≤ ICC < 0.75) for 15 chemokines and eight soluble receptors. However, five chemokines (GRO, IP-10, MIP-1β, BCA-1, and MIP-3α) had ICC < 0.4, suggesting biological variability.
Conclusion: Multiplex assays for plasma levels of selected chemokines and soluble receptors showed good to excellent assay detectability and repeatability. Most analytes also had good 3-year within-subject reproducibility, indicating that a single measurement of these analytes may be used to assess biomarker-disease associations.
PMCID: PMC3908322  PMID: 24600562
Chemokines; Soluble receptors; Within-subject variability; Biomarker; Limit of detection

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