Relation between steroid receptor status and body weight in breast cancer patients.

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.