Breast epithelial proliferation in postmenopausal women evaluated through fine-needle-aspiration cytology

The aim was to evaluate fine-needle-aspiration (FNA) cytology as a method of following breast epithelial proliferation in postmenopausal women during hormone replacement therapy (HRT).

Twelve healthy postmenopausal women were recruited and randomized to two different types of sequential HRT during 4 months of treatment. The women were administered continuous estradiol 50 micrograms/24 h with the addition of progestogen sequentially in the form of either vaginal progesterone gel 8 mg every 2nd day or medroxyprogesterone acetate 5 mg/day orally during 12 days per month for the complete treatment period. Fine-needle-aspiration biopsies were performed twice during the estrogen phases and twice during the estrogen plus progestogen phases of treatment. Breast epithelial proliferation was analyzed in these samples by immunocytochemistry to measure the content of the nuclear antigen Ki-67/MIB-1, which is expressed in proliferating cells.

From the 12 women, a total number of 47 FNA biopsies were taken. Thirty-eight of these aspirates, 19 from each of the estrogen and the estrogen plus progestogen phases, were evaluable for MIB-1 content (81%). There was a non-significant increase in levels of proliferation during the combined estrogen-progestogen phase (2.1%) compared with the estrogen-only phase (1.4%). These values were similar to those previously observed during the menstrual cycle in young fertile women.

We conclude that the FNA biopsy technique is feasible for studying proliferation not only in young, normally cycling women but also in the postmenopausal breast.