Histopathologic behavior of endometrial hyperplasia during tamoxifen therapy for breast cancer

The purpose of the present study is to prospectively evaluate the effects of tamoxifen on the pathological behavior of endometrial hyperplasias without atypia, diagnosed before the start of adjuvant endocrine therapy, in menopausal patients suffering from breast cancer.

Twenty-six patients suffering from estrogen-receptor positive breast cancer and candidate to receive adjuvant tamoxifen, were found to be affected by endometrial hyperplasias before the start of endocrine therapy. All women showed a baseline endometrial stripe, measured by transvaginal ultrasonography, thicker than 4 mm and the diagnosis of endometrial hyperplasia was made by hysteroscopy and endometrial biopsy. Two patients showing complex atypical hyperplasia underwent vaginal hysterectomy, whereas the remaining 24 patients, suffering from endometrial hyperplasia without atypia, were followed on a yearly basis during the period of tamoxifen intake, by hysteroscopy and endometrial biopsy.

Baseline histopathology showed simple and complex hyperplasia in 20 and in 4 patients, respectively. The median follow-up period was 38 months; in particular, all patients underwent endometrial assessment after 12 months, while 22, 16, 10 and 4 patients were followed-up after 24, 36, 48 and 60 months of tamoxifen therapy, respectively. Progression from complex hyperplasia to complex atypical hyperplasia (1 patient) and from complex and simple hyperplasia to adenocarcinomas (2 patients) was found within 24 months of tamoxifen intake in 3 patients (12.5%). In 2 patients (8.3%), a progression from simple to complex hyperplasia was detected within 36 months of tamoxifen treatment. In 13 patients (54.1%), stable histology of simple or complex hyperplasia was found, whereas 6 patients (25.0%), with focal hyperplasia harbored in an endometrial polyp, showed a normalization of endometrial histology after polyp resection.

Endometrial hyperplasias without atypia diagnosed before endocrine therapy for breast cancer in menopausal patients show an early and high progression-rate to atypical lesions under tamoxifen influence.