Timing of surgery in relation to the menstrual cycle and its influence on the survival of Japanese women with operable breast cancer.

It has been suggested that the timing of surgery during periods of unopposed estrogen circulation, when high blood levels of estrogen and low blood levels of progesterone exist, has a deleterious effect on the survival of premenopausal patients with breast cancer. We studied this controversial issue by examining the serum estradiol and progesterone levels of 38 premenopausal patients with primary breast cancer, and by analyzing data on 100 premenopausal patients treated for primary breast cancer. The survival of 31 patients who had undergone initial surgery between days 3 and 12 after their last menstrual period (group E) was compared with that of 69 patients who had undergone surgery between days 0 and 2 or from 13 days after their last menstrual period (group P). The overall survival of group E was significantly worse than that of group P (P = 0.049). This difference was especially notable in patients with node-positive tumors or tumors larger than 2 cm in size; however there was no significant difference in disease-free survival between the two groups. On a multivariate analysis, nodal status was the only significant prognostic factor for both overall and disease-free survival. Thus, these findings suggest that unopposed estrogen circulation may be detrimental to the overall survival of premenopausal women with breast cancer.