Breast Cancer Detection Demonstration Project data can determine whether the prognosis of breast cancer is affected by the time of surgery during the menstrual cycle.

The purpose of this study was to determine the feasibility of using Breast Cancer Detection Demonstration Project (BCDDP) data to ascertain whether the prognosis of breast cancer in premenopausal women is affected when surgery is performed relative to the different phases of the menstrual cycle. In the Louisville BCDDP only 40 cases were available for study, but even with this small number, the data indicate that survivorship was superior when the surgery was performed between days 7-20 of the menstrual cycle (P < 0.06). One thousand eighty-seven premenopausal women underwent surgery for breast cancer during the first 5 years of the national BCDDP, beginning in 1972. This large number of cases, plus the long period of follow-up should provide sufficient statistical power for us to evaluate if there is any relationship between the day of the menstrual cycle, the day surgery was performed, and prognosis. This feasibility study indicates that these women should be followed up and the appropriate statistical studies should be done.