Hormone replacement therapy and breast cancer risk in Kyushu University Hospital: supporting the Women's Health Initiative study.

Abstract

The influence of hormone replacement therapy (HRT) on breast cancer has not been clarified in Japan, however the Women's Health Initiative (WHI) trial recently showed breast cancer risk according to use of estrogen plus progestin. We assessed retrospectively the incidence of breast cancer in postmenopausal women who received HRT at our outpatients clinic. Among the patients registered at the postmenopausal clinic in Kyushu University Hospital from 1990 to 2003, 917 women who received HRT (estrogen plus progestin, 507 patients; estrogen only, 410 patients) after informed consent were examined by mammography or breast ultrasound tomography. Breast cancer occurred in nine patients: five patients who received estrogen plus progestin and four who received estrogen only. Four of five the patients who used estrogen plus progestin received HRT for more than 5 years. Breast cancer risk in patients who used estrogen plus progestin for more than 5 years seemed to be higher than those who used it for less than 5 years. This tendency is similar to the results of the WHI. In addition, breast cancer incidence in patients treated with HRT in our clinic seemed to be higher than the incidence in average Japanese women. Therefore, patients need to be given sufficient information before undergoing HRT.