Background To clarify lifestyle factors that affect the risk of pancreatic cancer among the Japanese population, a nested case-control study was conducted using data from the Hospital-based Epidemiologic Research Program at Aichi Cancer Center (HERPACC), Japan.
Methods The study subjects included 200 incident cases of pancreatic cancer and 2000 age-class frequency-matched cancer-free outpatients attending the baseline questionnaire of HERPACC in the period 1988-1999. Associations between lifestyles and the risk of pancreatic cancer were evaluated using odds ratios estimated by the unconditional logistic regression model, adjusting for potential confounding factors.
Results A positive family history of pancreatic cancer and a past or present history of diabetes significantly increased the risk of pancreatic cancer. In contrast, regular physical exercise, a regular bowel habit, and frequent consumption of raw vegetables appeared to be protective. Current alcohol drinkers showed decreased risk, but the opposite was the case for former drinkers. Current smoking did not affect the risk of pancreatic cancer, while former smokers showed a tendency for decreased risk. Compared with light smokers, heavy smokers showed a modest tendency for increase in risk, especially those who starting smoking at a younger age, but there were no clear tendencies for duration and pack-years of smoking.
Conclusions From these results it appears that smoking habit, which has long been considered a sole important determinant, has only a modest role, if any, in pancreatic cancer in Japanese.