Influence of timing of surgery during menstrual cycle on survival of premenopausal women with operable breast cancer

Whether timing of surgery in relation to the menstrual cycle influences the survival of premenopausal women with breast cancer is disputed. We have conducted a retrospective study of 221 premenopausal women treated by one surgeon (JAM) with a median follow-up of 9.6 years (range 0.6, 22.1 years). Patients operated on 3–12 days from last menstrual period (LMP) (group 1; N = 80) were compared with patients operated on 0–2 and 13–28 days from LMP (group 2; N = 141). By univariate analysis group 1 patients were found to have superior disease-free survival (DFS; CHI-SQUARED = 455, P = 0.03) and overall survival (OS: CHI-SQUARED = 6.76, P = 0.009), with LMP group ranking behind nodal status (n = 136: DFS; CHI-SQUARED = 40.73, P = 0.00001. OS; CHI-SQUARED = 41.09, p < 0.00001) and tumour size (n = 216: DFS; CHI-SQUARED = 19.89, p < 0.001. OS; CHI-SQUARED = 15.56, P = 0.0001) in importance. This difference remained significant when adjusted individually for nodal status, tumour size, age and treatment groups. The difference was not found to be significant in patients with tumours 3 cm (n = 146: DFS; CHI-SQUARED = 0.31, P = 058: OS; CHI-SQUARED = 0.16, P = 0.69), but was highly significant in patients with tumours> 3 cm (n = 70: DFS; CHI-SQUARED = 9.91, P = 0.0016: OS; CHI-SQUARED = 15.74, P = 0.0001). In multivariate analysis LMP group remained significant for both DFS and OS, and was independent from nodal status, tumour size and age. These data support the need for a prospective study.