Timing of surgery during the menstrual cycle and prognosis of breast cancer.

There are conflicting reports on the differential effect of surgery performed during the two phases of the menstrual cycle, namely, follicular and luteal, and prognosis of operable breast cancer. A statistical meta-analysis of the published evidence suggests a modest survival benefit of 15+/-4% when the operation is performed during the luteal phase. Further research in this area might provide a novel avenue to understand the natural history of breast cancer. A spin off from these studies might be the understanding of the importance of events that occur at the time of surgery in determining long term prognosis.