Glycemic index and glycemic load and risk of colorectal cancer: a population-based cohort study (JPHC Study)

The aim of this study was for the first time to assess the association between glycemic index (GI), glycemic load (GL), and colorectal cancer using a prospective Japanese population-based cohort. In our study participants aged 40-69 at baseline of the Japan Public Health Center-based prospective Study (JPHC Study) in 10 prefectural public health centers (PHC) were included. Subjects responding to the five-year follow-up survey (1995-1999) without previous history of cancer and missing data were included in the current analysis n = 73,501 (men n = 34,560 and women n = 38,941). We reported results as hazard ratios (HR) and 95 % confidence intervals (CI) by Cox proportional hazards modeling. The average follow-up time was 12.5 years (919,276 person-years). A total of 1,468 colorectal cancer cases were detected. Overall, no significant results were observed; however, GL was inversely nonsignificantly associated with colon cancer in men HR = 0.74 (95 % CI 0.51-1.09) and rectal cancer in women 0.52 (95 % CI 0.24-1.14). The GL tended to be inversely associated with proximal colon cancer among men 0.62 (95 % CI 0.36-1.08), while a positive association with the GI was observed among women 1.37 (95 % CI 0.88-2.14). Sensitivity analyses excluding the first three years of observation showed similar results. Results stratified by diabetes status, BMI, smoking and red meat were nonsignificant. In conclusion, the prospective JPHC Study suggests that the GI and GL do not have a substantial impact on the risk of colorectal cancer in Japanese adults.