Background and objectives: Studies have shown molecular, genetic and cellular changes in breast cancer during the menstrual cycle. Changes in proliferative and metastatic potential of breast cancer cells during menses could explain improved survival when tumors are surgically removed in the luteal phase. This study examined if timing of mammography/core biopsy (MAM-CB) also affected breast cancer prognosis (histological tumor grade).
Methods: Eighty-five premenopausal women undergoing MAM-CB at one clinic between March 1995 and February 1998 were retrospectively studied. All patients had Stage I or II breast cancer surgically treated. Patients were grouped by phase of menses at MAM-CB: follicular (F, Days 0-14) or luteal (L, Days 15-35). Groups were comparable in age, menarche, family history, nulliparity, breastfeeding, and total percentage of clinically palpable tumors. Pathological characteristics of the tumors (tumor size, tumor type, estrogen and progesterone receptor status, axillary lymph node status, the presence of lymphatic or vascular invasion and extranodal metastasis) was also comparable across the 2 groups.
Results: Low-grade tumors were more frequent in the MAM-CB group L, whereas high-grade tumors were more common in the MAM-CB group F (P = 0.002, chi2(4) = 17.06).
Conclusions: Timing of MAM-CB in relation to menses may be a factor influencing breast cancer outcome. Future studies examining the effect of menses on the outcome of breast cancer should consider the potential effect of the timing of MAM-CB.