Breast cancer and timing of surgery during menstrual cycle. A 5-year analysis of 385 pre-menopausal women.

It has been proposed that the timing of breast-cancer surgery in relation to menstrual phase has a prognostic impact on outcome. We carefully evaluated a combined 2-center series of 385 pre-menopausal women operated on for stage-I and stage-II breast cancer with a median follow-up of 5 years for a possible impact on outcome of the date of their last menstrual period (LMP) before surgery. The distribution of risk factors of the study cohort as well as prognostic indicators corresponded to previously published results. Nodal status, grading, and (in part) hormone-receptor status differentiate well between patient subgroups with high and low risk of relapse and death after breast-cancer surgery. In neither univariate nor multivariate analysis was any impact of the so-called "unopposed" estrogen secretion detected. We did not observe any effect of LMP on long-term survival in any of several prognostic subgroups, in particular in hormone-receptor-positive patients. From our results and from the literature, we conclude that LMP does not provide any prognostic information for outcome after breast-cancer surgery and therefore the proposed modification of scheduling of breast-cancer operations is not justified.