Tamoxifen and the endometrium: findings of pelvic ultrasound examination and endometrial biopsy in asymptomatic breast cancer patients.

The need for endometrial surveillance in breast cancer patients undergoing adjuvant treatment with tamoxifen is still controversial. In this study, 164 asymptomatic breast cancer patients (110 on treatment with tamoxifen, 20 mg/day, and 54 controls) were examined with pelvic ultrasound and endometrial biopsy. No differences in ultrasound and biopsy findings were observed in the pre- and perimenopausal group between patients treated with tamoxifen and controls. Postmenopausal patients on tamoxifen had a significantly thicker endometrium (mean ± SD, 7.2 ± 8.5 vs. 1.5 ± 4.3 mm, p=0.00002) and significantly larger uterine volume (mean ± SD, 63.2 ± 39.9 vs. 43.7 ± 38.8 cm3, p=0.0001) than controls. Fifty-four percent of patients on tamoxifen had an endometrial thickness ≥ 5 mm, often with multiple irregular sonolucencies suggesting the presence of cysts. Ultrasound findings, however, did not correlate with the presence of endometrial abnormalities on biopsy, and no endometrial cancer or atypical hyperplasia were found. This lack of correlation makes questionable the use of routine sonography in asymptomatic breast cancer patients on tamoxifen. Obtaining routine endometrial samples, on the other hand, may be difficult in some patients because of cervical stenosis or refusal. Until the benefits of endometrial surveillance will be proved, asymptomatic patients should not be submitted routinely to ultrasound examination or biopsy, but encouraged to report promptly any abnormal vaginal bleeding.