Objective: Our objective was to analyze the presence of estrogen and progesterone receptors in breast epithelial cells from healthy women during the follicular and luteal phase of the menstrual cycle.
Study design: We analyzed estrogen receptor and progesterone receptor variations in breast epithelial cells procured through fine-needle aspiration biopsy from 42 healthy volunteers during the menstrual cycle using immunocytochemical receptor analysis. Differences were assessed by chi 2 test and the Wilcoxon rank sum tests.
Results: Estrogen receptor was detected more often in women aspirated in the follicular (68%) than in the luteal (32%) phase (p < 0.001); progesterone receptor was detected in around 80% in both phases. In ovulating women who were aspirated twice during the same menstrual cycle the proportion of estrogen receptor-positive cells was reduced from 20% to 4% (p < 0.02); the progesterone receptor values were 17% and 24%.
Conclusion: Our data indicate an important difference in progesterone receptor variation in the breast as compared with the endometrium.