Variations in prognostic factors in primary breast cancer throughout the menstrual cycle

Aims: We investigated whether menstrual cycle dependent variations in progn ostic factors are detectable in malignant breast tissue. Methods: Since 1977 the Danish Breast Cancer Cooperative Group has collecte d population-based information about primary clinical data, treatment regim ens and follow-up status on Danish women with breast cancer. Information ab out last menstrual periods prior to surgery was obtained from files recorde d at the lime of admission for primary surgery. Included in this study were 1060 patients self-reported to be regularly menstruating and with a menstr ual period within 6 weeks of surgery and who were operated in a single-step procedure, None of the patients were current users of exogenous hormones a t the lime of surgery. Variations of prognostic factors throughout the mens trual cycle were evaluated. Results: Overall, no significant correlation between endogenous hormone flu ctuations and oestrogen receptor (ER) status and progesterone receptor (PgR ) status were found. Furthermore, we observed no cycle-dependent variation for mitotic index, lymph node involvement or tumour size. Conclusions: The classical prognostic factors in breast cancer did not diff er significantly throughout the menstrual cycle in the present study. (C) 2 000 Harcourt Publishers Ltd.