Night work might influence cancer risk, possibly via suppression of melatonin release. In a population-based case-control study conducted in Montreal, Quebec, Canada, between 1979 and 1985, job histories, including work hours, were elicited from 3,137 males with incident cancer at one of 11 anatomic sites and from 512 controls. Compared with men who never worked at night, the adjusted odds ratios among men who ever worked at night were 1.76 (95% confidence interval (CI): 1.25, 2.47) for lung cancer, 2.03 (95% CI: 1.43, 2.89) for colon cancer, 1.74 (95% CI: 1.22, 2.49) for bladder cancer, 2.77 (95% CI: 1.96, 3.92) for prostate cancer, 2.09 (95% CI: 1.40, 3.14) for rectal cancer, 2.27 (95% CI: 1.24, 4.15) for pancreatic cancer, and 2.31 (95% CI: 1.48, 3.61) for non-Hodgkin's lymphoma. Equivocal evidence or no evidence was observed for cancers of the stomach (odds ratio (OR) = 1.34, 95% CI: 0.85, 2.10), kidney (OR = 1.42, 95% CI: 0.86, 2.35), and esophagus (OR = 1.51, 95% CI: 0.80, 2.84) and for melanoma (OR = 1.04, 95% CI: 0.49, 2.22). There was no evidence of increasing risk with increasing duration of night work, with risks generally being increased across all duration categories. Results suggest that night work may increase cancer risk at several sites among men.

Diabetics may have a higher risk of cancer, notably liver and pancreatic cancers. Evidence about other cancer types remains sparse. The authors examined potential associations between diabetes and several types of cancer in a large multicancer case-control project carried out in Montreal, Canada, in the 1980s. This report, based on 3,107 male cancer cases and 509 population controls, uses information on diabetes and several covariates collected by interview. Adjusted odds ratios (ORs) and 95% confidence intervals (CI) were estimated for the associations between diabetes and each of 12 cancer types. Risks of pancreatic and liver cancers were increased among diabetics: adjusted ORs were 2.1 (95% CI: 1.0, 4.3) for pancreatic and 3.1 (95% CI: 1.1, 8.8) for liver cancer. The increased risk of pancreatic cancer was completely restricted to those with recent onset of diabetes; this was likely a manifestation of reverse causality. Conversely, the increased risk of liver cancer was independent of the interval between diabetes and cancer diagnoses. No associations were observed with melanoma, nonHodgkin's lymphoma, cancers of the esophagus, stomach, colon, rectum, lung, prostate, bladder and kidney. In conclusion, diabetes was associated with an increased risk of liver cancer among men, but with no other cancer type including pancreatic cancer. ' 2005 Wiley-Liss, Inc.

BackgroundWood dust is one of the oldest and one of the most common occupational exposures in the world. The present analyses examine the effect of lifetime exposure to wood dust in diverse occupational settings on lung cancer risk.MethodsWe conducted two population-based case–control studies in Montreal: Study I (1979–1986) included 857 cases and two sets of controls (533 population and 1349 cancer controls), and Study II (1996–2001) comprised 736 cases and 894 population controls. Detailed job histories were obtained by interview and each job was evaluated by expert chemist–hygienists to estimate the likelihood and level of exposure to many substances, one of which was wood dust. Odds ratios (ORs) were computed in relation to different indices of exposure to wood dust, adjusting for several covariates including smoking. Three datasets were analysed: Study I with population controls, Study I with cancer controls, and Study II.ResultsThe most frequently exposed occupations in our study population were in construction, timber and furniture making industries. We found increased risks of lung cancer for substantial cumulative exposure to wood dust in Study I with cancer controls, (OR = 1.4: 95% confidence interval 1.0;-2.0) and in Study II (OR = 1.7: 95% confidence interval 1.1-2.7). There were no excess risks of lung cancer in any of the three datasets among workers whose cumulative exposure was not substantial. These tendencies held equally within strata of low smokers and heavy smokers.ConclusionThere was evidence of increased risk of lung cancer among workers with substantial cumulative exposure to wood dust.Electronic supplementary materialThe online version of this article (doi:10.1186/1476-069X-14-1) contains supplementary material, which is available to authorized users.

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