Abstract

Obesity is known to adversely affect breast cancer prognosis. Since obesity is associated with increased oestrogen levels, and oestrogens are growth stimulators of oestrogen receptor (ER)-positive breast carcinomas, we evaluated the relationship between the ER and progesterone receptor (PR) status of the neoplastic tissue and obesity in a series of 615 breast cancer patients. Both ER and PR concentrations were significantly and positively correlated with obesity by multiple regression analysis. Furthermore, the estimated probability of having an ER+/PR+carcinoma was significantly higher in obese patients (odds ratio 2.65, 95% confidence interval 1.56-4.48). This association between receptor-positive status and obesity was observed both in premenopausal and postmenopausal patients. Our data suggest, therefore, that obesity plays a role in determining the ER status of breast cancer and raise the possibility that ER presence in breast carcinomas occurring in obese patients is not indicative of a favourable prognosis.