Timing of surgery during menstrual cycle and survival of premenopausal women with operable breast cancer.

Timing of operation in relation to menstrual phase might affect outlook in premenopausal women with operable breast cancer. We examined the records of 249 such women treated between 1975 and 1985, and compared overall and recurrence-free survival in those whose operation was 3-12 days after their last menstrual period (LMP) (group 1, n = 75) with those in whom it was 0-2 or 13-32 days after LMP (group 2, n = 174). Overall and recurrence-free survival were greatly reduced in group 1 women (p less than 0.001 for both). Actuarial survival at 10 years was 54% in group 1 versus 84% in group 2. This effect was independent of other factors, was of much the same importance as nodal status in multivariate analysis, was largely confined to histologically node-positive cases, seemed to be greater in women with small tumours (less than or equal to 2 cm), and was seen in patients with oestrogen-receptor positive and negative tumours. Thus phase of menstrual cycle at operation is of great importance for long-term outlook in premenopausal women with breast cancer.