Reciprocal effects of tamoxifen on hormonal cytology in postmenopausal women

OBJECTIVE: To evaluate the estrogenic effect of tamoxifen (TAM) therapy in postmenopausal women. STUDY DESIGN: The subjects were 26 postmenopausal women. The maturation index (MI), maturation value (MV) and karyopyknotic index (KPI) were evaluated based on hormonal cytology. Endometrial cytologic examinations and transvaginal ultrasonography were also performed. RESULTS: Of the 26 patients, 16 had low estrogenic activity from the viewpoint of hormonal cytology before TAM administration. During administration, their mean MV rose significantly, from 25.8 +/- 17.7 to 68.8 +/- 13.2, (mean +/- SD) and their mean KPI rose from 9.0 +/- 8.3 to 47.1 +/- 23.1. In contrast, among the 10 patients with high estrogenic activity, mean MV and KPI decreased from 62.9 +/- 8.4 and 27.2 +/- 16.9 to 58.4 +/- 7.7 and 17.7 +/- 16.1, respectively, with TAM administration. Mean endometrial thickness increased more significantly with TAM administration in the low estrogenic activity group than in the high estrogenic activity group. CONCLUSION: TAM had a reciprocal effect; no additional estrogenic effect was seen in patients with high estrogenic activity. Conversely, an estrogenic effect was seen in those with low estrogenic activity. An individualized gynecologic evaluation based on hormonal cytology is useful in selecting patients who will be more susceptible to TAM-induced endometrial abnormality.