American Association for Cancer Research - A new study has found that the more “western” the diet - choosing red meat, starches and sweets - the higher the risk for breast cancer among post-menopausal Chinese women. According to researchers who conducted the analysis at Fox Chase Cancer Center in Philadelphia, Harvard University, Shanghai Cancer Institute, and Vanderbilt University, the findings mark the first time a specific association between a western diet and breast cancer has been identified in Asian women.

The study, published in the July 2007 issue of Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, is the latest set of findings derived from the Shanghai Breast Cancer Study, conducted in the 1990s by Wei Zheng, M.D., Ph.D., M.P.H, and colleagues at Vanderbilt University. It was funded through grants from the National Institutes of Health and the American Cancer Society. The Fox Chase researchers identified dietary habits among women in the study based on their reported eating habits, classifying them as either “meat-sweet” or “vegetable-soy” eaters.

“The Shanghai data gave us a unique look at a population of Chinese women who were beginning to adopt more western-style eating habits,” said, Marilyn Tseng, Ph.D. associate member in the population science division at Fox Chase. “We found an association between a western-style diet and breast cancer was pronounced in postmenopausal women, especially heavier women with estrogen receptor-positive tumors.”

Breast cancers marked by the excessive production of estrogen receptors (ER+ breast cancers) form the majority of breast cancers and are often associated with obesity. According to Tseng, there seems to be a specific interaction between obesity and western cuisine among postmenopausal women that drives breast cancer, although the study did not offer a specific mechanism.

Through in-person interviews with the Shanghai study participants and residents of Shanghai, researchers established the existence of two primary dietary patterns - a “meat-sweet” diet and a “vegetable-soy” diet. The “meat-sweet” diet is characterized by various meats, primarily pork but also poultry, organ meats, beef and lamb, and shrimp, saltwater fish, and shellfish, as well as candy, dessert, bread, and milk. The “vegetable-soy” pattern is associated with various vegetables, soy-based products, and freshwater fish.

The “meat-sweet” pattern was significantly associated with increased risk of breast cancer among overweight postmenopausal women. Specifically, high intake of the “meat-sweet” pattern was associated with a greater than twofold increased risk of ER+ breast cancer among these women. The results showed no overall association of breast cancer risk with the “vegetable-soy” pattern.

“Our study suggests the possibility that the “meat-sweet” pattern interacts with obesity to increase breast cancer risk,” Tseng said. “Low consumption of a western dietary pattern plus successful weight control may protect against breast cancer in a traditionally low-risk Asian population that is poised to more broadly adopt foods characteristic of western societies.”