Original Articles : Development of breast cancer during postmenopausal hormone therapy in Korea

Objective: The clinicopathologic characteristics of patients with breast cancer arising during postmenopausal hormone therapy were determined. Methods: The study included 29 patients diagnosed with breast cancer during postmenopausal hormone therapy (HT group) and 285 patients diagnosed with breast cancer after menopause who did not receive HT (non-HT group). The data were collected at the three affiliated Hospitals of the Catholic University of Korea over a 10 year period. Tumor size, lymph node metastasis, the presence of estrogen receptors, the stage at the time of diagnosis, the method of treatment, the type of operation, the recurrence rate, and the mortality rate were compared between the two groups. Results: The HT group had smaller tumors than the non-HT group (P=0.0032). In the HT and non-HT groups, 55.2% and 28.6% of the tumors were T1, respectively. In the HT and non-HT groups, 53.9% and 13.4% of the tumors were well differentiated, respectively (P=0.0026). The 5-year survival rate was 100% and 87.6% in the HT and non-HT groups, respectively (P<0.001). Conclusion: Postmenopausal Korean women who developed breast cancer while taking HT had a higher rate of well differentiated tumors, a higher rate of tumors <2 cm in size, and a higher 5-year survival rate than women who developed breast cancer when not taking HT.