Predicting response to cytotoxic drugs--the endocrine part of the story.

The substantial reduction in risk of recurrence and mortality in premenopausal breast cancer patients of estrogen deprivation as treatment for early ER+ breast cancer is well accepted. Surgical, radiotherapeutic or medical approaches to ovarian ablation/suppression all seem to be similarly effective and appear to be at least partially additive to the reduction seen with chemotherapy. Cytotoxic treatment of premenopausal women also frequently elicits a reduction in frequency and regularity of menstruation and sometimes a complete and permanent amenorrhea as a reflection of reduced ovarian activity. While it is certain that the associated reduction in estrogenic exposure of patients contributes to the overall effectiveness of chemotherapy in some premenopausal women the degree to which this is the case is a subject of vigorous debate. Furthermore, the extent to which chemotherapy induced ovarian suppression impacts on molecular predictors of chemotherapy benefit is poorly understood and recommendations for further study of this issue are made.