We recently reported a significant positive association between 25-hydroxyvitamin D [25(OH)D], the accepted biomarker of vitamin D status, and prostate cancer risk. To further elucidate this association, we examined the influence of vitamin D binding protein (DBP), the primary transporter of vitamin D compounds in the circulation. Prediagnostic serum concentrations of DBP were assayed for 950 cases and 964 matched controls with existing 25(OH)D measurements within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of Finnish men. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI), and statistical tests were two-sided. Serum DBP modified the association between serum 25(OH)D and prostate cancer, with higher risk for elevated 25(OH)D levels observed primarily among men having DBP concentrations above the median (OR=1.81, 95% CI 1.18–2.79 for highest vs. lowest quintile, p-trend = 0.001) compared to those with DBP below the median (OR=1.22, 95% CI 0.81–1.84, p-trend 0.97; p-interaction = 0.04). Serum DBP was not associated with prostate cancer risk overall (OR=0.96, 95% CI 0.70–1.33 for highest vs. lowest quintile); however, high serum DBP was associated with significantly decreased risk of prostate cancer in men with lower (
vitamin D binding protein; 25-hydroxyvitamin D; prostate cancer; serum biomarkers; prospective study
Binding of advanced glycation end products (AGEs) to their receptor (RAGE) increases oxidative stress and inflammation, and may be involved in liver injury and subsequent carcinogenesis. Soluble RAGE (sRAGE) may neutralize the effects mediated by AGEs/RAGE complex. Epidemiologic studies examining sRAGE or AGEs in association with liver cancer are lacking. We examined the associations between prediagnostic serum concentrations of sRAGE or Nε-(carboxymethyl)-lysine (CML)-AGE and hepatocellular carcinoma (HCC) in a case-cohort study within a cohort of 29,133 Finnish male smokers who completed questionnaires and provided a fasting blood sample in 1985–1988. During follow-up beginning 5 years after enrollment through April 2006, 145 liver cancers occurred. Serum concentrations of sRAGE, CML-AGE, glucose, and insulin were measured in cases and 485 randomly sampled cohort participants. Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) were available on most cases and a subset of the study population. Weighted Cox proportional hazards regression was used to calculate relative risks (RR) and 95% confidence intervals (CI), adjusted for age, years of smoking, and body mass index. sRAGE and CML-AGE concentrations were inversely associated with liver cancer (sRAGE: RR, highest versus lowest tertile, 0.77; 95% CI, 0.48–1.24; Ptrend=0.28; continuous RR, 0.86; 95% CI, 0.75–0.99; CML-AGE: RR, highest versus lowest tertile, 0.19; 95% CI, 0.10–0.35; Ptrend <0.0001; continuous RR, 0.74; 95% CI, 0.65–0.84). Further adjustment for glucose and insulin, or exclusion of cases with chronic HBV or HCV, did not change the associations.
Our results support the hypothesis that sRAGE is inversely associated with liver cancer. The findings need confirmation, particularly in populations that include women and non-smokers.
sRAGE; CML-AGE; case-cohort; incidence; men
The primary circulating form of vitamin D is 25-hydroxy-vitamin D (25(OH)D), a modifiable trait linked with a growing number of chronic diseases. In addition to environmental determinants of 25(OH)D, including dietary sources and skin ultraviolet B (UVB) exposure, twin and family-based studies suggest that genetics contribute substantially to vitamin D variability with heritability estimates ranging from 43% to 80%. Genome-wide association studies (GWAS) have identified SNPs located in four gene regions associated with 25(OH)D. These SNPs collectively explain only a fraction of the heritability in 25(OH)D estimated by twin and family based studies. Using 25(OH)D concentrations and GWAS data on 5,575 subjects drawn from 5 cohorts, we hypothesized that genome-wide data, in the form of (1) a polygenic score comprised of hundreds or thousands of SNPs that do not individually reach GWAS significance, or (2) a linear-mixed-model for genome-wide complex trait analysis, would explain variance in measured circulating 25(OH)D beyond that explained by known genome-wide significant 25(OH)D associated SNPs. GWAS identified SNPs explained 5.2% of the variation in circulating 25(OH)D in these samples and there was little evidence additional markers significantly improved predictive ability. On average a polygenic score comprised of GWAS identified SNPs explained a larger proportion of variation in circulating 25(OH)D than scores comprised of thousands of SNPs which were on average, non-significant. Employing a linear-mixed-model for genome-wide complex trait analysis explained little additional variability (range 0-22%). The absence of a significant polygenic effect in this relatively large sample suggests an oligogenetic architecture for 25(OH)D.
vitamin D; heritability; genome wide association; polygenic score
Despite a well-established link between obesity and renal cell carcinoma (RCC), the mechanism through which obesity acts to increase cancer risk is unclear. Adiponectin, leptin and resistin are adipocyte-secreted peptide hormones that may influence RCC development through their demonstrated effects on inflammation, insulin resistance and cell growth and proliferation. We conducted a nested case–control study to evaluate whether prediagnostic serum adiponectin, leptin and resistin levels are associated with RCC risk. This case–control study (273 cases and 273 controls) was nested within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort of Finnish male smokers. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated using conditional logistic regression models, with analyte levels modeled continuously and categorically (defined using quartiles among controls). High adiponectin levels were significantly associated with reduced RCC risk (Quartile 4 versus Quartile 1: OR = 0.52, 95% CI = 0.30–0.88; P trend = 0.01). This association remained upon additional adjustment for body mass index at blood collection and exclusion of cases diagnosed within the first 2 years of follow-up. In addition, model adjustment for adiponectin resulted in a substantial attenuation of the association between BMI and RCC (OR per 5kg/m2 changed from 1.19 to 1.05). No clear associations with RCC were observed for leptin or resistin. Our results suggest that elevated levels of circulating adiponectin are associated with decreased subsequent risk of RCC. These findings provide the strongest evidence to date, suggesting that the association between obesity and RCC is mediated at least in part through the effects of low adiponectin.
Prospective investigations of circulating vitamin D concentrations suggest inverse associations with colorectal cancer risk, although inconsistencies remain and few studies have examined the impact of season. The authors conducted a prospective case-control study of 239 colon cancer cases and 192 rectal cancer cases (diagnosed in 1993–2005) and 428 controls matched on age and blood collection date within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, a cohort study of Finnish male smokers. Baseline serum 25-hydroxyvitamin D (25(OH)D) concentrations were categorized using a priori defined cutpoints of <25, 25–<37.5, 37.5–<50, 50–<75, and ≥75 nmol/L and by season-specific and season-standardized 25(OH)D quartiles. Conditional logistic regression models yielded multivariate-adjusted odds ratios for the predefined cutpoints of 0.63, 0.91, 0.73, 1.00 (referent), and 1.44 for colon cancer and 0.64, 0.58, 0.84, 1.00, and 0.76 for rectal cancer, respectively (all 95% confidence intervals included 1.00). Colon cancer risks were significantly elevated for the highest season-specific and season-standardized quartiles versus the lowest quartiles (OR = 2.11 (95% CI: 1.20, 3.69) and OR = 1.88 (95% CI: 1.07, 3.28), respectively), while rectal cancer risk estimates were null. These results provide no evidence to support an inverse association between vitamin D status and colon or rectal cancer risk; instead, they suggest a positive association for colon cancer.
cohort studies; colorectal neoplasms; prospective studies; vitamin D
Iron is an essential micronutrient that can have carcinogenic effects when at high or low concentrations. Previous studies of iron in relation to gastric cancer have not assessed subtype-specific relationships. We used the prospective ATBC Cancer Prevention Study to assess whether iron metrics were associated with gastric cardia cancer (GCC) and gastric noncardia cancer (GNCC).
We selected 341 incident gastric cancer cases (86 cardia, 172 noncardia, and 83 non-specified), accrued during 22 years of follow-up, and 341 individually matched controls. We measured prediagnostic serum iron, ferritin, unsaturated iron binding capacity (UIBC), and C-reactive protein. Total iron binding capacity (TIBC) and transferrin saturation were estimated from these metrics. Dietary iron exposures were estimated from a food frequency questionnaire. Multivariable logistic regression was used for analysis.
Serum iron metrics were not associated with GCC, except for a potential ‘n’-shaped relationship with TIBC (global p=0.038). GNCC was inversely associated with serum ferritin (global p=0.024), serum iron (global p=0.060) and, possibly, transferrin saturation. TIBC appeared to share a ‘u’shaped relationship with GNCC (global p=0.033). Dietary iron exposures were not associated with either subsite. Adjustment for Helicobacter pylori and gastric atrophy had little effect on observed associations.
We found little evidence for the involvement of iron exposure in the pathogenesis of GCC. GNCC was associated with an iron profile similar to that of iron deficiency.
Helicobacter pylori; Iron; Nested Case-Control Studies; Prospective Studies; Stomach Neoplasms
Excess alcohol consumption adversely affects one-carbon metabolism and increases the risk of liver disease and liver cancer. Conversely, higher folate levels have been inversely associated with liver damage. The current study investigated the effects of alcohol and one-carbon metabolite intake on liver cancer incidence and liver disease mortality within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study.
Cox proportional hazards modeling was used to calculate hazard ratios and 95% confidence intervals (CIs) in a population of 27,086 Finnish males with 194 incident liver cancers and 213 liver disease deaths. In a nested case-control subset (95 liver cancers, 103 controls), logistic regression was used to calculate odds ratios and 95% CIs for serum one-carbon metabolites in relation to liver cancer risk.
Daily alcohol consumption of more than 20.44 g was associated with an increased risk of both liver cancer incidence (Hazard Ratio (HR) 1.52, 95%CI 1.06–2.18) and liver disease mortality (HR 6.68, 95%CI 4.16–10.71). These risks were unaffected by one-carbon metabolite intake. Similarly, in the case-control study, none of the serum one-carbon metabolites were associated with liver cancer.
The current study provided no convincing evidence for a protective association of one-carbon metabolite intake or serum level on the risk of liver cancer or liver disease mortality.
The one previous prospective study of vitamin D status and risk of urinary bladder cancer found that male smokers with low serum 25-hydroxy-vitamin D (25(OH)D) were at a nearly 2-fold increased risk. We conducted an analysis of serum 25(OH)D and risk of bladder cancer in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Study, and examined whether serum vitamin D binding protein (DBP) concentration confounded or modified the association.
375 cases of bladder cancer were matched 1:1 with controls based on age (+/- 5 years), race, sex, and date of blood collection (+/- 30 days). Conditional logistic regression was used to estimate odds ratios and 95% confidence intervals of bladder cancer by pre-diagnosis levels of 25(OH)D.
We found no strong or statistically significant association between serum 25(OH)D and bladder cancer risk (Q1 vs. Q4: OR=0.84 95% CI=0.52–1.36; p-trend = 0.56). Further adjustment for serum DBP did not alter the findings, nor was there a main effect association between DBP and risk.
In contrast to the one previous study of this hypothesis, we observed no association between vitamin D status and risk of bladder cancer; this difference could be due to the inclusion of women and non-smokers in the current study population, or to differences in the distribution of vitamin D concentrations between the two study populations.
These findings may contribute to future meta-analyses and help elucidate whether the vitamin D-bladder cancer association varies across populations.
Urinary bladder neoplasms; 25-hydroxyvitamin D; Case-control studies
There are no observational studies or controlled trials of amyotrophic lateral sclerosis (ALS) and circulating α-tocopherol (vitamin E) for prevention of ALS. This study addresses that gap.
The study population comprised 29,127 Finnish male smokers, aged 50–69 years, who participated in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, which is both a prospective cohort and a randomized, double-blind, placebo-controlled trial of α-tocopherol (50 mg/day) and β-carotene (20 mg/day). Serum α-tocopherol and β-carotene was assayed at baseline (1985–1988). Follow-up (median 16.7 years) continued through 2004. ALS cases were identified through the national Hospital Discharge Register with diagnostic verification by hospital records and death certificates.
During 407,260 person-years of follow-up, 50 men were identified with ALS. For men with serum α-tocopherol concentration above the median (≥11.6 mg/l), the age-adjusted relative risk (RR) compared to α-tocopherol below the median, was 0.56 (95% confidence interval= 0.32–0.99), p=0.046. The RR among α-tocopherol supplement recipients was 0.75 (95% CI=0.32–1.79), p=0.52. Neither serum β-carotene level nor β-carotene supplementation was associated with ALS.
The results are consistent with a hypothesized protective effect of α-tocopherol on ALS risk. However, pooled analyses of cohorts with serum and controlled trials are needed to clarify the role of α-tocopherol in ALS risk.
Amyotrophic lateral sclerosis; vitamin E; cohort studies; risk factors in epidemiology
High concentrations of circulating 25-hydroxyvitamin D [25(OH)D] have been associated with elevated pancreatic cancer risk. As this is contrary to an expected inverse association between vitamin D status and cancer, we examined whether vitamin D binding protein (DBP), the primary carrier of vitamin D compounds in circulation, plays a role in this relationship. Prediagnostic serum DBP and 25(OH)D were studied in relation to risk of pancreatic cancer in a nested case-control study of 234 pancreatic cancer cases and 234 controls in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of Finnish men. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression, and statistical tests were two-sided. We found that DBP and 25(OH)D were correlated (r=0.27; p<0.0001), and DBP was inversely associated with pancreatic cancer risk (OR=0.66, 95% CI=0.39–1.12, for the highest vs. lowest quartile; p-trend=0.02). Importantly, this association appeared to have a threshold between quartiles 2–4 and quartile 1, and was primarily evident among men with concurrent high 25(OH)D concentrations (OR=0.33, 95% CI=0.16–0.70 for highest vs. lowest quartile; p-trend=0.002), with no association in men with lower serum 25(OH)D (OR=1.28, 95% CI=0.62–2.61 for highest vs. lowest quartile, p-trend 0.63, p-interaction= 0.01). Men with higher 25(OH)D concentrations and serum DBP below the median showed greatly elevated risk of pancreatic cancer (OR=5.01, 95% CI 2.33–10.78, for highest vs. lowest quartile; p-trend < 0.0001), while risk was weakly inversely associated with serum 25(OH)D when DBP concentrations were higher (p-interaction = 0.001). Taken together, our findings indicate that higher DBP concentrations may sequester more 25(OH)D and reduce free 25(OH)D bioavailability. Simultaneous examination of DBP and 25(OH)D may be important in determining the association of vitamin D with cancer risk.
Vitamin D Binding Protein; 25-Hydroxyvitamin D; Pancreatic Cancer; serum biomarkers; prospective study
Circulating total cholesterol has been inversely associated with cancer risk; however, the role of reverse causation and the associations for high density lipoprotein (HDL) cholesterol have not been fully characterized. We examined the relationship between serum total and HDL cholesterol and risk of overall and site-specific cancers among 29,093 men in the ATBC Study cohort.
Fasting serum total and HDL cholesterol were assayed at baseline, and 7,545 incident cancers were identified during up to 18 years of follow-up. Multivariable proportional hazards models were conducted to estimate relative risks.
Higher serum total cholesterol concentration was associated with decreased risk of cancer overall (RR for comparing high versus low quintile=0.85, 95%CI=0.79–0.91; P trend < 0.001; >276.7 versus <203.9 mg/dL), and the inverse association was particularly evident for cancers of the lung and liver. These associations were no longer significant, however, when cases diagnosed during the first nine years of follow-up were excluded. Greater HDL cholesterol was also associated with decreased risk of cancer (RR for high versus low quintile=0.89, 95%CI=0.83–0.97; P trend=0.01; >55.3 versus <36.2 mg/dL). The inverse association of HDL cholesterol was evident for cancers of lung, prostate, liver, and the hematopoietic system, and the associations of HDL cholesterol with liver and lung cancers remained after excluding cases diagnosed within 12 years of study entry.
Our findings suggest that prior observations regarding serum total cholesterol and cancer are largely explained by reverse causation. Although chance and reverse causation may explain some of the inverse HDL associations, we cannot rule out some etiologic role for this lipid fraction.
serum; cholesterol; high density lipoprotein cholesterol; cancer; risk; prospective; cohort
Oesophageal cancers rank as the eighth most common cancer and the sixth most common cause of cancer death, worldwide. Gastric atrophy, as determined by a low serum pepsinogen I/II ratio, may be associated with an increased risk of oesophageal squamous cell carcinoma (OSCC). Ghrelin, a hormone which, like pepsinogen, is produced in the fundic glands of the stomach, may be a sensitive and specific marker of gastric atrophy, but its association with OSCC is not known.
To examine the relationship between baseline serum ghrelin concentration and subsequent risk of OSCC, we conducted a nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study. 82 cases of OSCC were matched (1:1) by age and date of blood draw to controls from the ATBC study. Serum ghrelin was measured by radioimmunoassay. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using conditional logistic regression with adjustment for potential confounders.
For those individuals in the lowest quartile of serum ghrelin, compared to those in the highest, the multivariate odds ratio of subsequent OSCC was 6.83 (95% CI: 1.46, 31.84). These associations were dose dependent (P for trend = 0.005 for both), and independent of the effects of low pepsinogen I/II ratio (a marker of gastric fundic atrophy) and Helicobacter pylori infection. The significance of these associations remained even for individuals developing OSCC up to 10 years after baseline ghrelin measurement, though they become attenuated after 10 years.
Lower baseline concentrations of serum ghrelin were associated with an increase in risk of OSCC. Further studies are needed to confirm this finding in other populations and to explore the role of ghrelin in the aetiology of OSCC.
ghrelin; oesophageal squamous cell carcinoma; atrophy
Telomere length plays an important role in chromosomal stability and tumorigenesis, and its measurement in peripheral white blood cell DNA may be a predictor of the development of lung cancer.
Using a new method - monochrome multiplex quantitative PCR -which reduces measurement variability, we compared telomere length relative to standard DNA in white blood cell DNA in 229 incident male lung cancer cases and 229 matched controls within the prospective Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study of male smokers.
Median (10th, 90th percentile) telomere length was 1.13 (0.86, 1.45) in cases and 1.08 (0.85, 1.38) in controls (P = 0.038). Telomere length was inversely associated with pack-years of smoking (Spearman correlation r = −0.16, P = 0.02) among controls. Compared to subjects with shorter telomere length (≤ median), subjects with greater telomere length (> median) had a 1.6-fold (95% CI, 1.06–2.36) increased risk of lung cancer. There was a significant linear relationship between quartiles of telomere length and risk of lung cancer (odds ratios (95% confidence intervals) by quartile: 1.00, 0.98 (0.55–1.73), 1.62 (0.95–2.77), and 1.50 (0.84–2.68); Ptrend = 0.05). In addition, subgroup analysis showed that greater telomere length was associated with increased risk of lung cancer among heavy smokers (> 38 years) (OR, 1.90; 95% CI, 1.00–3.59) but not among light smokers (≤ 38 years) (OR, 1.08; 95% CI, 0.56–2.11) (Pinteraction = 0.01).
Our results suggest that greater telomere length may be associated with higher risk of lung cancer among male smokers.
Telomere length; lung cancer; cohort study
Studies suggest a decreased risk of high-grade prostate cancer in men with lower circulating total cholesterol, and that statins may protect against aggressive disease. Confirmation in additional populations and examination of associations for lipoprotein subfractions are needed.
We examined prostate cancer risk and serum total and HDL cholesterol in the ATBC Study cohort (n=29,093). Cox proportional hazards models were used to estimate the relative risk of total (n=2,041), non –aggressive (n=829), aggressive (n=461), advanced (n=412), and high-grade (n=231) prostate cancer by categories of total and HDL cholesterol.
After excluding the first 10 years of follow-up, men with higher serum total cholesterol were at increased risk of overall (≥240 vs. <200 mg/dL: HR=1.22, 95% CI 1.03-1.44, p-trend=0.01) and advanced (≥240 vs. <200 mg/dL: HR=1.85, 95% CI 1.13–3.03, p-trend=0.05) prostate cancer. Higher HDL cholesterol was suggestively associated with a decreased risk of prostate cancer regardless of stage or grade.
In this population of smokers, high serum total cholesterol was associated with higher risk of advanced prostate cancer, and high HDL cholesterol suggestively reduced the risk of prostate cancer overall. These results support previous studies and, indirectly, support the hypothesis that statins may reduce the risk of advanced prostate cancer by lowering cholesterol.
Cholesterol; HDL; Prospective Studies; Prostatic Neoplasms; Epidemiology; Risk; Molecular; Biomarker
Many epidemiologic studies have examined the association between CRP and risk of cancer with inconsistent results.
We conducted two nested, case-control studies in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study and Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial to test whether pre-diagnostic circulating CRP concentrations were associated with pancreatic adenocarcinoma. Between 1985 and 2004, 311 cases occurred in ATBC and between 1994 and 2006, 182 cases occurred in PLCO. Controls (n=510 in ATBC, n=374 in PLCO) were alive at the time the case was diagnosed and were matched by age, date of blood draw, sex, and race. We used conditional logistic regression adjusted for smoking to calculate odds ratios (OR) and 95% confidence intervals (CI) for pancreatic cancer.
CRP concentrations (ng/ml) tended to be inversely or not associated with pancreatic cancer risk in ATBC, PLCO, and combined analyses (per standardized quintile increase in CRP, continuous OR= 0.94, 95% CI 0.89, 0.99; OR=0.99, 95% CI 0.95, 1.04; OR=0.98, 95% CI 0.95, 1.01, respectively). In combined analyses, we observed a significant interaction (p-interaction=0.02) such that inverse associations were suggestive in younger (OR=0.95; 95% CI, 0.90–1.01), but not older participants.
Our results do not support the hypothesis that higher CRP concentrations are associated with incident pancreatic cancer.
Our results highlight the importance of investigating more specific biomarkers for inflammation that may reflect the biological mechanisms underlying pancreatic cancer in prospective cohort studies.
CRP; ATBC; PLCO; Pancreatic; Case-Control
We introduce an innovative multilocus test for disease association. It is an extension of an existing score test that gains power over alternative methods by incorporating a parsimonious one-degree-of-freedom model for interaction. We use our method in applications designed to detect interactions that generate hypotheses about the functionality of prostate cancer (PRCA) susceptibility regions.
Our proposed score test is designed to gain additional power through the use of a retrospective likelihood that exploits an assumption of independence between unlinked loci in the underlying population. Its performance is validated through simulation. The method is used in conditional scans with data from stage II of the Cancer Genetic Markers of Susceptibility PRCA genome-wide association study.
Our proposed method increases power to detect susceptibility loci in diverse settings. It identified two high-ranking, biologically interesting interactions: (1) rs748120 of NR2C2 and subregions of 8q24 that contain independent susceptibility loci specific to PRCA and (2) rs4810671 of SULF2 and both JAZF1 and HNF1B that are associated with PRCA and type 2 diabetes.
Our score test is a promising multilocus tool for genetic epidemiology. The results of our applications suggest functionality for poorly understood PRCA susceptibility regions. They motivate replication study.
Gene-gene interaction; Score test; Prostate cancer
Diabetes, obesity, and cigarette smoke, consistent risk factors for pancreatic cancer, are sources of oxidative stress in humans that could cause mitochondrial DNA (mtDNA) damage and increase mtDNA copy number.
To test whether higher mtDNA copy number is associated with increased incident pancreatic cancer, we conducted a nested case-control study in the Alpha-Tocopherol Beta Carotene Cancer Prevention (ATBC) Study cohort of male smokers, aged 50-69 years at baseline. Between 1992 and 2004, 203 incident cases of pancreatic adenocarcinoma occurred (follow-up: 12 years) among participants with whole blood samples used for mtDNA extraction. For these cases and 656 controls, we calculated odds ratios (OR) and 95% confidence intervals using unconditional logistic regression, adjusting for age, smoking, and diabetes history. All statistical tests were two-sided.
Higher mtDNA copy number was significantly associated with increased pancreatic cancer risk (highest vs. lowest mtDNA copy number quintile, OR=1.64, 95%CI=1.01-2.67, continuous OR=1.14, 95% CI 1.06-1.23), particularly for cases diagnosed during the first 7 years of follow-up (OR=2.14,95% CI=1.16-3.96, p-trend=0.01, continuous OR=1.21, 95% CI 1.10-1.33), but not for cases occurring during follow-up of 7 years or greater (OR= 1.14, 95% CI=0.53-2.45, continuous OR=1.05, 95% CI 0.93-1.18).
Our results support the hypothesis that mtDNA copy number is associated with pancreatic cancer and could possibly serve as a biomarker for pancreatic cancer development.
Thyroid hormones may influence risk of cancer through their role in cell differentiation, growth, and metabolism. One study of circulating thyroid hormones supports this hypothesis with respect to prostate cancer. We undertook a prospective analysis of thyroid hormones and prostate cancer risk in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study.
Within the ATBC Study, a randomized controlled trial of α-tocopherol and β-carotene supplements and cancer incidence in male smokers, 402 prostate cancer cases were sampled. Controls were matched 2∶1 to cases on age and date of blood collection. Odds ratios (OR) and 95% confidence intervals (CI) of prostate cancer were estimated for quintiles of serum total and free thyroxine (T4), thyroid-stimulating hormone (TSH), thyroid-binding globulin (TBG), and by categories of thyroid status.
Men with serum higher TSH had a decreased risk of prostate cancer compared to men with lower TSH (Q5 vs. Q1–4: OR = 0.70, 95% CI: 0.51–0.97, p = 0.03). When the T4 and TSH measurements were combined to define men as hypothyroid, euthyroid or hyperthyroid, hypothyroid men had a lower risk of prostate cancer compared to euthyroid men (OR = 0.48, 95% CI = 0.28–0.81, p = 0.006). We observed no association between hyperthyroid status and risk, although the number of hyperthyroid men with prostate cancer was small (n = 9).
In this prospective study of smokers, men with elevated TSH and those classified as being in a hypothyroid state were at decreased risk of prostate cancer. Future studies should examine the association in other populations, particularly non-smokers and other racial/ethnic groups.
Vitamin D compounds inhibit prostate tumorigenesis experimentally, but epidemiological data are inconsistent with respect to prostate cancer risk, with some studies suggesting non-significant positive associations.
The 25-hydroxyvitamin D [25(OH)D]-prostate cancer relation was examined in a nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of 50–69 year old Finnish men. We matched 1,000 controls to 1,000 cases diagnosed during up to 20 years of follow-up based on age (± 1 year) and blood collection date (± 30 days). Conditional multivariate logistic regression models estimated odds ratios (OR) and 95% confidence intervals (CI). All statistical significance testing was two-sided.
Cases had non-significantly 3% higher serum 25(OH)D(P=0.19). ORs (95% CIs) for increasing season-specific quintiles of 25(OH)D concentrations were 1.00 (reference), 1.29 (0.95–1.74), 1.34 (1.00–1.80), 1.26 (0.93–1.72), and 1.56(1.15–2.12)(Ptrend=0.01). Analyses based on pre-specified clinical categories and season-adjusted values yielded similar results. These findings appeared stronger for aggressive disease (OR [95% CI] for fifth quintile of serum 25(OH)D=1.70 [1.05–2.76]), and among men with greater physical activity (1.85 (1.26–2.72), Ptrend=0.002), higher serum total cholesterol (2.09 (1.36–3.21), Ptrend=0.003) or alpha-tocopherol (2.00 (1.30–3.07), Ptrend=0.01), higher intakes of total calcium (1.82 (1.20–2.76), Ptrend=0.01) or vitamin D (1.69 (1.04–2.75), Ptrend=0.08), or those who had received the trial alpha-tocopherol supplements (1.74 (1.15–2.64), Ptrend=0.006).
Our findings indicate that men with higher vitamin D blood levels are at increased risk of developing prostate cancer.
Greater caution is warranted with respect to recommendations for high-dose vitamin D supplementation and higher population target blood levels.
serum; vitamin D; prostate cancer; risk; cohort
Cancers of the upper gastrointestinal tract remain a substantial cause of morbidity and mortality worldwide. Ghrelin is a hormone produced in the oxyntic glands of the stomach, and under conditions of chronic inflammation and atrophy, serum ghrelin concentrations decrease. However, the relationship between ghrelin and the risk of gastric and esophagogastric junctional cancers has not been investigated.
We conducted a nested case–control study within the Finnish Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study to examine the relationship between serum ghrelin concentration and the risk of gastric noncardia adenocarcinoma (GNCA) and esophagogastric junctional adenocarcinoma (EGJA). Data from 261 GNCA patients, 98 EGJA patients, and 441 control subjects were analyzed. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using logistic regression with adjustment for potential confounders. Lag analysis was also performed to investigate the temporal nature of the associations between baseline serum pepsinogen I and ghrelin in GNCA and EGJA patients. All statistical tests were two-sided.
Lower concentrations of serum ghrelin were statistically significantly associated with an increased risk of both GNCA (adjusted OR = 1.75, 95% CI = 1.49 to 2.04; P < .001) and EGJA (adjusted OR = 1.56, 95% CI = 1.28 to 1.89, P < .001). A multivariable model found that the risk of both GNCA and EGJA were statistically significantly increased for those individuals in the lowest quartile of serum ghrelin levels compared with those in the highest quartile (OR of GNCA = 5.63, 95% CI = 3.16 to 10.03; OR of EGJA = 4.90, 95% CI = 2.11 to 11.35). The statistical significance of these associations remained even after restricting the analysis to those patients who developed cancer more than 10 years after baseline serum ghrelin measurements.
Low baseline concentrations of serum ghrelin were associated with a statistically significant increase in the risk of GNCA and EGJA, suggesting a potential role for gastric hormones in carcinogenesis.
Vitamin E compounds exhibit prostate cancer preventive properties experimentally, but serologic investigations of tocopherols, and randomized controlled trials of supplementation in particular, have been inconsistent. Many studies suggest protective effects among smokers and for aggressive prostate cancer, however.
We conducted a nested case-control study of serum α-tocopherol and γ-tocopherol and prostate cancer risk in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, with 680 prostate cancer cases and 824 frequency-matched controls. Multivariate-adjusted, conditional logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CIs) for tocopherol quintiles.
Serum α-tocopherol and γ-tocopherol were inversely correlated (r = −0.24, p<0.0001). Higher serum α-tocopherol was associated with significantly lower prostate cancer risk (OR for the highest vs. lowest quintile = 0.63, 95% CI 0.44–0.92, p-trend 0.05). By contrast, risk was non-significantly elevated among men with higher γ-tocopherol concentrations (OR for the highest vs. lowest quintile = 1.35, 95% CI 0.92–1.97, p-trend 0.41). The inverse association between prostate cancer and α-tocopherol was restricted to current and recently former smokers, but was only slightly stronger for aggressive disease. By contrast, the increased risk for higher γ-tocopherol was more pronounced for less aggressive cancers.
Our findings indicate higher α-tocopherol status is associated with decreased risk of developing prostate cancer, particularly among smokers. Although two recent controlled trials did not substantiate an earlier finding of lower prostate cancer incidence and mortality in response to supplementation with a relatively low dose of α-tocopherol, higher α-tocopherol status may be beneficial with respect to prostate cancer risk among smokers. Determining what stage of prostate cancer development is impacted by vitamin E, the underlying mechanisms, and how smoking modifies the association, is needed for a more complete understanding of the vitamin E-prostate cancer relation.
Advanced glycation end-products (AGEs) accumulate in human tissue proteins during aging, particularly under hyperglycemia conditions. AGEs induce oxidative stress and inflammation via the receptor for AGEs (RAGE) and soluble RAGE (sRAGE) can neutralize the effects mediated by RAGE/ligand engagement.
We examined the association between Nε-(carboxymethyl)lysine (CML), a prominent AGEs, and sRAGE and colorectal cancer risk in a prospective case-cohort study nested within a cancer prevention trial among 29,133 Finnish male smokers. Among study subjects who were alive without cancer five years after baseline (1985–1988), we identified 483 incident colorectal cancer cases and randomly sampled 485 subcohort participants as the comparison group with the follow-up to April 2006. Baseline serum levels of CML-AGE, sRAGE, glucose and insulin were determined. Weighted Cox proportional hazard regression models were used to calculate relative risks (RR) and 95% confidence intervals (CI).
Comparing highest with lowest quintile of sRAGE, the RR for incident colorectal cancer was 0.65 (95% CI: 0.39, 1.07; P value for trend = 0.03), adjusting for age, years of smoking, body mass index, and CML-AGE. Further adjustment for serum glucose strengthened the association (RR: 0.52; 95% CI: 0.30, 0.89; P value for trend = 0.009). Highest quintile of CML-AGE was not associated with an increased risk of colorectal cancer (multivariate RR: 1.20; 95% CI: 0.64, 2.26).
Higher prediagnostic levels of serum sRAGE were associated with lower risk of colorectal cancer in male smokers.
This is the first epidemiologic study to implicate the receptor for advanced glycation end-products in colorectal cancer development.
advanced glycation end-products; soluble receptor for advanced glycation end-products; colorectal cancer; risk; case-cohort; inflammation
Published studies suggesting a relationship between vitamin D and some common cancers sparked interest in the association of vitamin D with head and neck cancers. Prolonged darker months in Finland are associated with lower levels of ultraviolet B radiation, raising concerns about low vitamin D levels.
We used a nested case-control study in the prospective Alpha-Tocopherol Beta Carotene (ATBC) Study of male smokers in Finland, to examine the relationship between serum 25(OH)D and risk of developing squamous cancers of the head and neck. Using conditional logistic regression we calculated the multivariate adjusted odds ratio (OR) and confidence interval (CI) comparing those with serum 25(OH)D adequate levels of 50–<75 nmol/L to those <25.0.
We identified incident cancers of the oral cavity (n=134), pharynx (n=48), and larynx (n=158). Median serum vitamin D was 31 nmol/L (interquartile range 21–48), which is below the 50 nmol/L cutoff considered adequate for bone and overall health. Comparing those with serum 25(OH)D below 25 nmol/L to those 50–<75 nmol/L as the referent, the OR was 1.35 (95% CI: 0.53, 3.43, p-trend=0.65) for overall head and neck cancers. Stratification by cancer sub-sites of the oral cavity, pharynx and larynx (p-trend= 0.93, 0.78, 0.26 respectively) or by season of blood draw also showed no association.
Our study showed no association between serum 25(OH)D and risk of head and neck cancers.
This study does not support the hypothesis that greater vitamin D exposure would reduce the risk of developing head and neck squamous cancers.
Head and neck/oral cancers; Diet; alcohol; smoking; and other lifestyle risk factors; vitamin D; Cohort; Finland
Cigarette smoking, obesity, type 2 diabetes, and to a less extent, meat cooked at high temperatures are associated with pancreatic cancer. Cigarette smoke and foods cooked at higher temperatures are major environmental sources of advanced glycation end-products (AGEs). AGEs accumulate during hyperglycemia and elicit oxidative stress and inflammation through interaction with the receptor for AGEs (RAGE). Soluble RAGE (sRAGE) acts as an anti-inflammatory factor to neutralize AGEs and block the effects mediated by RAGE. In this study, we investigated the associations of prediagnostic measures of Nε-(carboxymethyl)-lysine (CML)-AGE and sRAGE with pancreatic cancer in a case-cohort study within a cohort of 29,133 Finnish male smokers. Serum samples and exposure information were collected at baseline (1985-1988). We measured CML-AGE, sRAGE, glucose and insulin concentrations in fasting serum from 255 incident pancreatic cancer cases that arose through April 2005 and from 485 randomly sampled subcohort participants. Weighted Cox proportional hazard regression models were used to calculate relative risks (RR) and 95% confidence intervals (CI), adjusted for age, years of smoking and body mass index. CML-AGE and sRAGE were mutually adjusted. CML-AGE levels were not associated with pancreatic cancer (fifth compared with first quintile, RR (95% CI): 0.68 (0.38-1.22), Ptrend = 0.27). In contrast, sRAGE levels were inversely associated with pancreatic cancer (fifth compared with first quintile, RR (95% CI): 0.46 (0.23-0.73), Ptrend = 0.002). Further adjustment for glucose or insulin levels did not change the observed associations. Our findings suggest that sRAGE is inversely associated with pancreatic cancer risk among Finnish male smokers.
advanced glycation end-products; soluble receptor for advanced glycation end-products; pancreatic cancer; risk; prospective