Cellular characteristics of nipple aspiration fluid during the menstrual cycle in healthy premenopausal women

Fifteen healthy premenopausal female volunteers underwent weekly nipple asp iration of ductal fluid from both breasts during two menstrual cycles to in vestigate the variability of the cellular profile of the ductal fluid. Duct al fluid was successfully obtained using breast massage and nipple-areolar suction from 247/280 (89%) breasts. 83% of samples available for cytologica l analysis were cellular and 30% of cellular aspirates contained ductal epi thelial cells identified using standard morphological criteria. No signific ant variation in cell number or cell type was identified during the menstru al cycle. All samples tested had an 'H' score of zero for oestrogen recepto r. Seven out of 14 women expressed the proliferation marker Mcm-2 in the ce lls of at least one of the specimens, with no evidence of a menstrual cycle influence on expression. In conclusion, the cellular profile of breast duc tal fluid did not vary consistently during the menstrual cycle, permitting future breast cancer screening studies incorporating serial nipple aspirati ons to be performed independent of the phase of the cycle.