Dominique S. Michaud

BackgroundFindings on water and total fluid intake and bladder cancer are inconsistent; this may, in part, be due to different levels of carcinogens in drinking water. High levels of arsenic and chlorinated by-products in drinking water have been associated with elevated bladder cancer risk in most studies. A pooled analysis based on six case–control studies observed a positive association between tap water and bladder cancer but none for nontap fluid intake, suggesting that contaminants in tap water may be responsible for the excess risk.ObjectivesWe examined the association between total fluid and water consumption and bladder cancer risk, as well as the interaction between water intake and trihalomethane (THM) exposure, in a large case–control study in Spain.MethodsA total of 397 bladder cancer cases and 664 matched controls were available for this analysis. Odds ratios (OR) were estimated using unconditional logistic regression, controlling for potential confounders.ResultsTotal fluid intake was assoc...

Background: Hyperinsulinemia and insulin resistance have been proposed as underlying mechanisms for the increase in pancreatic cancer among long-standing diabetics and obese individuals. An association between serum insulin levels and pancreatic cancer risk was reported in a recent study, but the population was composed of heavy smokers and their findings may not be generalizable to nonsmokers. Methods: Pancreatic cancer cases and matched controls were obtained from four large-scale prospective cohorts to examine the association between prediagnostic plasma levels of C-peptide and insulin and pancreatic cancer. One hundred ninety-seven pancreatic cancer cases were diagnosed during a maximum of 20 years of follow-up, after excluding cases diagnosed within 2 years of blood collection or with baseline diabetes. We estimated OR and confidence intervals (CI) using conditional logistic regression with adjustment for pancreatic cancer risk factors. Results: Prediagnostic plasma C-peptide was positively associated with pancreatic cancer risk (OR, 1.52; 95% CI, 0.87-2.64, highest compared with the lowest quartile, Ptrend = 0.005). The association was not modified by body mass index or physical activity but seemed to be slightly stronger among never smokers than ever smokers. Fasting C-peptide and insulin were not related to pancreatic cancer; however, we observed a strong linear association for nonfasting C-peptide and pancreatic cancer (OR, 4.24; 95% CI, 1.30-13.8, highest versus lowest quartile, Ptrend < 0.001). Conclusions: Based on our finding of a strong positive association with nonfasting C-peptide levels, we propose that insulin levels in the postprandial state may be the relevant exposure for pancreatic carcinogenesis; however, other studies will need to examine this possibility. (Cancer Epidemiol Biomarkers Prev 2007;16(10):2101–9)

Two previous cohort studies reported positive associations between tooth loss or periodontitis and pancreatic cancer risk. Data on periodontal disease were obtained at baseline and every other year thereafter in a cohort of 51 529 male health professionals aged 40–75 years. A total of 216 patients were diagnosed with incident pancreatic cancer during 16 years of follow-up. Multivariable relative risks (RRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models controlling for potential confounders, including detailed smoking history. All statistical tests were two-sided. Compared with no periodontal disease, history of periodontal disease was associated with increased pancreatic cancer risk (overall, multivariable RR = 1.64, 95% CI = 1.19 to 2.26; P = .002; crude incidence rates: 61 versus 25 per 100 000 person-years; among never smokers, multivariable RR = 2.09, 95% CI = 1.18 to 3.71; P = .01; crude incidence rates: 61 versus 19 per 100 000 person-years). In contrast, baseline number of natural teeth and cumulative tooth loss during follow-up were not strongly associated with pancreatic cancer. The association between periodontal disease and increased risk of pancreatic cancer may occur through plausible biologic mechanisms, but confirmation of this association is necessary.

In a prospective cohort study, a close to two-fold elevated risk of bladder cancer was found among men reporting a history of gonorrhoea (relative risk=1.92, 95% CI=1.10–3.33). Our finding warrants further examination of the role of gonorrhoea in bladder carcinogenesis.

Background: Nitrosamines, which are known bladder carcinogens, or their precursors are found in certain meat items, and concentrations of these compounds are especially high in bacon. Only 3 cohort studies, all with Objective: The aim was to examine the association between specific meat items and bladder cancer in 2 large prospective studies. Design: We analyzed data from 2 cohorts with up to 22 y of follow-up and 808 incident bladder cancer cases. Detailed data on meat were obtained from multiple food-frequency questionnaires administered over time. Multivariate relative risks (RRs) and 95% CIs were estimated by using Cox proportional hazards models with control for potential confounders, including detailed smoking history. Results: Men and women with a high intake of bacon (≥5 servings/wk) had an elevated risk of bladder cancer compared with those who never ate bacon (multivariate RR = 1.59; 95% CI = 1.06, 2.37), although the overall association was not statistically significant (P for trend = 0.06). However, the association with bacon was stronger and became statistically significant after the removal of individuals who indicated having “greatly” changed their red meat (men) or bacon (women) intake during the 10 y before baseline (multivariate RR = 2.10; 95% CI = 1.24, 3.55; P for trend = 0.006). A positive association was also detected for intake of chicken without skin, but not for chicken with skin or for other meats, including processed meats, hot dogs, and hamburgers. Conclusions: In these 2 cohorts combined, frequent consumption of bacon was associated with an elevated risk of bladder cancer. Other studies with data on specific meat items are necessary to confirm our findings.

In this issue, Stolzenberg-Solomon et al. report that higher circulating 25-hydroxy-vitamin D [25(OH)D] concentrations are associated with a higher risk of pancreatic cancer in the Alpha-Tocopherol Beta-Carotene (ATBC) cancer prevention cohort. Based on the large literature on vitamin D and cancer, this finding is most unexpected and should be interpreted with caution. These results

Background: Diabetes appears to be associated with the development of pancreatic cancer. Three large prospective cohort studies observed a statistically significant relationbetween obesity and pancreatic cancer risk. Dietary patterns have been associated with fasting insulin levels and risk of diabetes. To determine whether dietary patterns are associated with pancreatic cancer risk, we analyzed data from two large prospective cohort studies. Methods: We combined data for men and women to obtain a total of 366 cases of incident pancreatic cancer from a total of 124 672 eligible participants. Dietary data were obtained from food frequency questionnaires in 1986 for men and in 1984 for women. We identified two major dietary patterns, prudent and western, by factor analysis. The prudent pattern was characterized by high fruit and vegetable intake; the western pattern was characterized by high meat and high fat intakes. Multivariable relative risks (RRs) were adjusted for potential confounders, including smoking and body mass index. Results: In the pooled analysis of men and women, no associations were observed between the prudent pattern (RR = 1.32, 95% confidence interval [CI] = 0.66 to 2.63, for highest versus lowest quintile) or the western pattern (RR = 0.91, 95% CI = 0.57 to 1.47, for highest versus lowest quintile) and the risk of pancreatic cancer. Stratifying by body mass index or physical activity did not change the associations. Conclusion: Dietary patterns were not associated with the risk of pancreatic cancer in two large cohort studies of men and women.