A case-control study of dietary and nondietary risk factors for breast cancer in Shanghai.

A case-control study of breast cancer (186 cases, 186 population, and 186 hospital controls) was conducted in Shanghai, China, between 1982 and 1984. This population has a high daily caloric intake (population control mean, 2394 kcal) and low percentage of calories from fat (22.7%) compared to Western populations. Cases have a significantly greater daily caloric intake than controls, primarily because of increased consumption of monounsaturated fat for which the relative risk is 1.89 for the highest compared to the lowest quintile (P = 0.02). This finding requires cautious interpretation but seems worthy of further study in populations with similar dietary practices.