Dietary factors and breast cancer risk in Vaud, Switzerland.

The relationship between dietary factors and the risk of breast cancer was investigated in a case-control study conducted in the Canton of Vaud, Switzerland as a pilot phase for a larger cooperative study within the SEARCH Programme of the International Agency for Research on Cancer (Lyon, France). A total of 107 incident, histologically confirmed cases of breast cancer and 318 controls admitted to hospital for acute, nonhormone-related, gynecological, metabolic, or neoplastic disorders were interviewed. Significant direct trends in risk were observed with total energy intake [relative risk (RR) for highest vs. lowest intake tertile = 1.9] and, after allowance for energy intake, with frequency of consumption of various types of meat (RR = 2.1 for the highest tertile), cheese (RR = 2.7), and alcohol (RR = 2.1). Significant protections, on the order of 40-60% reductions for the highest vs. lowest consumption tertile, were conferred by total green vegetable consumption, selected types of vegetables and fruits (cucumbers, onions, pears), and a summary index of beta-carotene intake (RR = 0.4 for highest consumption tertile). Thus the present study confirmed the existence of an unfavorable dietary pattern for breast cancer risk (characterized by high-calorie, selected sources of animal fat and alcohol intake). Moreover, a significant protection could be gained by consuming a diet rich in vegetables and perhaps fruits.