Seasonal variation in estrogen and progesterone receptor levels in breast cancer - a factor in data interpretation

It is still widely accepted that evaluation of estrogen and progesterone re ceptors (ER, PR) in breast cancer tissue is one of the basic predictive ind icators of hormonal therapy success. Evaluation of hormonal receptors is us ually done once at the time of biopsy or surgery on the breast regardless o f the effect of time. In a retrospective evaluation of 1301 medical records of breast cancer patients the authors wanted to identify any time period d ependence in quantitative or qualitative hormonal status. Steroid receptors were measured in breast cancer tissues by cytosol-based ligand-binding tec hnique. The results suggest a strong time period dependence in hormonal sta tus. In premenopausal patients simultaneous evaluation of ER/PR revealed an increased frequency of both positive receptors in the autumn months, and a decrease in the spring months. In postmenopausal patients, both positive r eceptors were found more likely in the summer months and both negative in t he late winter months. Our results suggest that one evaluation of hormonal receptor status does not necessarily provide an accurate estimate of the ho rmonal status in breast cancer patients.