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Background: Type 2 diabetes mellitus (T2DM) is associated with an increased risk of colorectal cancer (CRC); however, studies differentiating between subsites of CRC are limited. We investigated how diabetes mellitus (DM) was associated with subsite-specific CRC risk in men and women., Methods: The Netherlands Cohort Study on diet and cancer is a prospective study among 120 852 men and women aged 55-69 years old at baseline in 1986. Information on DM, anthropometric, dietary and lifestyle factors was self-reported at baseline. T2DM was defined as the diagnosis of DM after 30 years of age. Incident CRC cases were identified by record linkage with the Netherlands cancer registry and the Dutch pathology registry. After 17.3 years of follow-up, 1735 incident male CRC cases and 1321 female CRC cases were available for analyses. Subsite-specific hazard ratios (HRs) for CRC were estimated in case-cohort analyses using Cox regression., Results: At baseline, 3.1% of subcohort members reported T2DM, of whom 80% were diagnosed after 50 years of age. Multivariable-adjusted models showed that the risk of proximal colon cancer was significantly increased in women with T2DM versus women without T2DM (HR=1.80, 95% confidence interval: 1.10-2.94). There was no association between T2DM and the risk of overall CRC, distal colon cancer and rectal cancer in women. In men, T2DM was not associated with overall CRC (HR=0.98, 95% confidence interval: 0.64-1.50), or with risk at any subsite., Conclusions: This prospective study showed an increased risk of proximal colon cancer in women with T2DM compared with non-T2DM women.

The authors investigated the associations between bowel movement and constipation frequencies and colorectal cancer (CRC) endpoints among men in the Netherlands Cohort Study on Diet and Cancer (n = 58,279) and explored whether dietary fiber intake may modify associations. After 13.3 years (1986-1999), 1,207 CRC cases and 1,753 subcohort members were available for case-cohort analyses. Multivariate analyses showed a significantly increased hazard ratio for CRC overall and rectal cancer in men who reported having a bowel movement 1-2 times per day (second-highest category) as compared with once a day (CRC: hazard ratio (HR) = 1.29, 95% confidence interval (CI): 1.09, 1.53 (P(trend) < 0.001); rectal cancer: HR = 1.50, 95% CI: 1.15, 1.95 (P(trend) = 0.001)). Hazard ratios for CRC overall and rectal cancer were significantly decreased and lowest in men who reported suffering from constipation sometimes or more often versus never (CRC: HR = 0.76, 95% CI: 0.58, 0.98 (P(trend) = 0.02); rectal cancer: HR = 0.57, 95% CI: 0.35, 0.90 (P(trend) = 0.01)). No trends in the associations with proximal or distal colon cancer risk were observed. Interactions with dietary fiber intake were not significant. In this study, frequent bowel movements were associated with an increased risk of rectal cancer in men, and constipation was associated with a decreased risk.

Dietary flavonoids are hypothesized to be protective against colorectal cancer, yet findings have been inconsistent. We examined the association of dietary flavonol, flavone and catechin intake with colorectal cancer endpoints within the Netherlands Cohort Study (NLCS). In addition, we explored whether body mass index (BMI) may be an effect modifier of this association. The NLCS includes 120,852 men and women who were 55-69 years and completed a self-administered questionnaire at baseline in 1986. A case-cohort approach was used for data processing and analysis. After 13.3 years, 1,444 male and 1,041 female colorectal cancer cases were available for estimation of hazard ratios and 95% confidence intervals for quintiles of flavonoid intake. After adjustment for potential confounders, no association of total flavonol and flavone intake and total catechin intake with colorectal cancer endpoints was observed. Analyses stratified for BMI showed significant inverse trends in the association of total catechin intake, (+)-catechin intake and (-)-epicatechin intake with rectal cancer in men with a BMI>or=25 kg/m2 and in the association of total catechin intake and intake of kaempferol, myricetin and all individual catechins with colorectal cancer, in particular colon cancer, in women with a BMI<25 kg/m2. In conclusion, our findings generally do not support an association of dietary flavonol, flavone and catechin intake with colorectal cancer endpoints. Dietary catechin intake may be associated with a decreased rectal cancer risk in overweight men. Dietary flavonol and catechin intake may be associated with a decreased colorectal cancer risk in normal weight women., (Copyright (c) 2009 UICC.)