Menstrual timing of treatment for breast cancer

Although the hormone dependency of breast cancer has been recognized for nearly a century, the influence on disease progression of cyclical hormonal levels among premenopausal women has not been extensively researched. The findings of recent studies, assessing the effect on prognosis of the hormonal milieu at the time of surgery, have been conflicting. However, several reports have noted improved survival among patients with positive, axillary lymph nodes surgically treated in the later phase of the menstrual cycle when progesterone levels are elevated. Biologic support for the influence of menstrual timing is provided by cyclical patterns of cell division and cell death observed in normal breast tissue as well as potential tumor cell dissemination during surgery among patients with positive axillary nodes. Immune parameters, which also respond to cycling endogenous hormones, may influence the metastatic potential of circulating tumor cells. Comparisons among studies of menstrual timing of surgery have been complicated by differences in cycle divisions, extent of primary surgery, frequency of adjuvant therapy, duration of follow-up, and analytic procedures. Although several clinicians are now scheduling breast surgery of premenopausal women in relation to day of the menstrual cycle, a majority of surgeons have deferred consideration of menstrual timing until additional research is available. While waiting 5-10 years for the results of prospective studies, additional retrospective analyses, using carefully collected data, may provide clinical guidance. With increasing concern for issues related to women's health, multidisciplinary studies will be required to adequately characterize the influence of the menstrual cycle and other aspects of women's reproductive physiology on breast cancer and other medical conditions.