Surgical procedure can explain varying influence of menstrual cycle on prognosis of premenopausal breast cancer patients

The mechanism of how menstrual cycle influences prognosis of premenopausal breast cancer patients is still unclear. In an analysis of 266 premenopausal patients we could confirm that patients who were operated on during the progestagenic phase (day 0–2 and 13–35) of the menstrual cycle showed an improved clinical outcome. However, if one-step surgery (tumour excision and definitive surgery on 1 day) was performed prognosis did not correlate with menstrual cycle (p = 0.8, log rank test). But, patients who underwent two-step surgery during the progestagenic phase showed a significantly longer disease-free survival (p < 0.001) and overall survival (p = 0.002) than patients in the oestrogenic phase. The effect was confined to node positive tumours (p = 0.003) and to hormone receptor positive tumours (p = 0.03). Our analysis suggests that if after diagnostic tumour excision intratumoural growth regulation is disturbed, and if tumour cells remain after excision (as in axillary lymphnodes), the proliferative potential of these hormone-dependent cells might be increased in an unopposed oestrogenic setting, thus facilitating metastatic spread.