White Rice Consumption and Risk of Colorectal Cancer Among Japanese Americans: The Multiethnic Cohort Study

Background: White rice is a staple food for Japanese, a population at high risk for colorectal cancer (CRC). We investigated the association between white rice intake and CRC among Japanese Americans in the Multiethnic Cohort (MEC) study. Methods: The MEC study is a prospective study established in Hawaii and California in 1993-1996. Usual dietary intake was assessed using a validated quantitative food frequency questionnaire at baseline. Cox proportional hazards models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for quartiles of intake and to perform trend tests across sex -specific quartiles with adjustment for relevant confounders. Results: We identified 1,553 invasive CRC cases among 49,136 Japanese Americans (23,595 men and 25,541 women) during a mean follow-up of 19 years. White rice consumption was not associated with overall CRC incidence in men (Ptrend = 0.11) or women (Ptrend = 0.56). After excluding participants with a history of diabetes, the inverse associations were significant for CRC (Ptrend = 0.03, HR for quartile 4 [Q4] vs quartile 1 [Q1], 0.81; 95% CI, 0.64-1.03) and tumors of the distal colon (Ptrend = 0.006, HR for Q4 vs Q1, 0.66; 95% CI, 0.44-0.99) among men but not women. Conclusion: White rice consumption was not associated with an increased risk of overall CRC among Japanese Americans. An inverse association was observed with risk of CRC and distal colon cancer in men without a history of diabetes.