A Case of Breast Cancer with a Rapid Decrease in Tumor Size after Cessation of Hormone Replacement Therapy

Abstract

We report a case of breast cancer in which the size of the tumor shrank rapidly after discontinuation of hormone replacement therapy (HRT). The patient was a 52-year-old woman who noticed a mass in her left breast in March. Echography revealed a hypoechoic mass of 16 mm in size in the upper-inner quadrant of her left breast. The pathological diagnosis by core needle biopsy was invasive ductal carcinoma, ER(+ : 95%), PgR(+ : 80%), and HER2(1+). She continued placing an adhesive skin patch of estradiol and norethisterone for menopausal symptoms since she was 51 years old, but we told her to discontinue it in April. Breast echography just before surgery showed a significant reduction in tumor size from 16 mm to 8 mm. The interruption of HRT seemed to decrease the blood level of estradiol and in effect diminish the size of the tumor. It is clear that long-term HRT increases the risk of breast cancer tumorigenesis, and even short-term HRT, as in this case, may lead to latent tumor growth.