Soy Food Intake and Pancreatic Cancer Risk: The Japan Public Health Center-based Prospective Study

Background: Although the poor prognosis and increasing incidence of pancreatic cancer highlight the need for prevention strategies, few lifestyle risk factors for pancreatic cancer have yet been identified. Soybeans contain various bioactive compounds. However, the association between soy food intake and pancreatic cancer risk remains unknown. Methods: The Japan Public Health Center-based Prospective Study is a cohort study conducted in a general Japanese population. To determine the association of soy food intake and pancreatic cancer incidence, we analyzed 90,185 participants who responded to a questionnaire on medical history and lifestyle factors, including dietary factors based on a food frequency questionnaire in 19951998, using Cox proportional hazards models. Results: During a median follow-up of 16.9 years, 577 cases of pancreatic cancer were identified. In the multivari-ate-adjusted model, total soy food intake was statistically significantly associated with an increased risk of pancreatic cancer [HR for the highest vs. lowest intake quartile: 1.48; 95% confidence interval (CI), 1.15-1.92; P-trend = 0.007]. Among soy foods, nonfermented soy food intake showed a statistically significant positive association with pancreatic cancer (HR, 1.41; 95% CI, 1.09-1.81; P-trend = 0.008), whereas fermented soy food intake showed no association (HR, 0.96; 95% CI, 0.73-1.26; P-trend = 0.982). Conclusions: Higher intake of soy foods, particularly nonfermented soy foods, might increase pancreatic cancer risk. Impact: This study is the first to report an association between the intake of various soy foods and pancreatic cancer risk. Further studies are required to confirm our findings.