261 Sequential vs. simultaneous administration of tamoxifen and medroxy progesterone acetate in advanced breast cancer

Overprolonged adjuvant tamoxifen therapy in breast cancer

While adjuvant tamoxifen therapy given continuously for 2-3 years can lead to a modest improvement in survival rates in early breast cancer, there is no evidence that prolonging tamoxifen administration beyond that time is likely to improve survival rates any further in unselected cases. In the case of advanced disease, an alternating tamoxifen/progestagen regimen has been shown to increase the response rate and also its duration, beyond that to be expected from either agent alone. The next generation of adjuvant trials in breast cancer needs to explore the potential of an alternating tamoxifen/megestrol regimen.

The structure and function of progesterone receptors in breast cancer

This paper is a review of the clinical role of progesterone receptors (PR) in the management of breast cancer, and the use of synthetic progestins in treatment of the metastatic disease. Also reviewed are our basic molecular studies dealing with the structure of human breast cancer PR, focusing on the two hormone binding proteins (the A- and B-receptors) and the role of phosphorylation. A model for the structure of PR and their subcellular compartmentalization following hormone treatment is presented.