SURVIVAL OF PREMENOPAUSAL WOMEN WITH BREAST-CARCINOMA - EFFECTS OF MENSTRUAL TIMING OF SURGERY

BACKGROUND. It is controversial whether the timing of tumor excision r elative to the menstrual cycle influences the survival of patients wit h breast carcinoma. METHODS. Premenopausal patients (n = 614) who had surgery for invasive, nonmetastatic breast carcinoma during the period 1978-1988 participated in an epidemiologic survey, reporting their me nstrual cycle length and the date of their last menses. We ascertained deaths from any cause before 1993. RESULTS. Using Cox modeling, we fo und a nonlinear variation in the relative risk (RR) of death according to the timing of surgery during the menstrual cycle. The curve was be st described by a cosine transformation of a 28-day cycle. For patient s who had breast carcinoma surgery on the estimated day of ovulation t he risk of death was 0.59 (95% confidence limits [CL] = 0.39-0.89, P = 0.013) compared with patients who had surgery at the approximate time of menses. We observed this for patients treated in 1978-1981 (RR = 0 .43, 95% CL = 0.23-0.83, P = 0.011) and 1982-1983 (0.25, 95% CL = 0.10 -0.63, P = 0.003), but not in 1984-1988 (1.48, 95% CL = 0.64-3.4). The difference observed for 1984-1988 was explained by a significant impr ovement in the mortality rate (P = 0.0004) for women whose surgery too k place during menses or near to the date predicted for the next mense s. No such improvement for women who underwent breast carcinoma surger y around the time of ovulation was observed during the period 1984-198 8. These changes were not explained by the performance of lumpectomy o r the increasing interval between biopsy and tumor excision. CONCLUSIO NS. The shape of the survival curve contradicted the idea that it coul d be explained by levels of circulating estradiol or progestrone. Beca use observations that surgery was affected by menstrual timing seem no t to have persisted beyond the mid-1980s, this study should not be use d to support recommendations that surgeons perform breast carcinoma su rgery on any particular day of the menstrual cycle. (C) 1998 American Cancer Society.