Clinical factors of the risk of hyperplastic endometry processes on tamoxifen therapy with breast cancer: Retrospective population study

Background. One of the main stages of the treatment of breast cancer (BC) is endocrine therapy with tamoxifen or aromatase inhibitors. Five years of adjuvant tamoxifen therapy reduces the risk of disease recurrence by 39%. Tamoxifen was approved by the U.S. Food and Drug Administration in 1977 as a treatment for ER-positive BC. However, sometime after the start of tamoxifen's wide use, reports have been published on its long-term adverse effects. Most common were hot flashes, gynecological symptoms (vaginal dryness, vaginal discharge), depression, forgetfulness, sleep changes, weight gain, and decreased libido. However, more serious adverse events such as venous thromboembolic disease and endometrial hyperplasia or cancer are the most clinically significant. The article presents the results of a retrospective population-based study on assessing hyperplastic processes of the endometrium (HPE) in patients with breast cancer during TAM therapy, conducted in 2017, approved by the Ethics Committee of the Scientific Research of the Russian Medical Academy of Continuing Professional Education. Aim. To identify clinical factors that may increase the risk of HPE during tamoxifen therapy in patients with a history of breast cancer living in the Moscow region. Materials and methods. We retrospectively reviewed 230 case histories of patients with breast cancer. Of these, 120 patients who received TAM therapy had the following HPE risk factors: average age, menopausal status, body mass index, and duration of TAM therapy. Results. It was found that patients with HPE taking TAM were older (p=0.017), more likely to be postmenopausal (p=0.035), overweight (p=0.023), and received TAM for a longer period (p=0.028) than patients without HPE. Conclusion. The data obtained indicate the need for continuous monitoring by gynecologists of patients with breast cancer taking tamoxifen, paying particular attention to women from high-risk groups, namely older postmenopausal women with high body mass index receiving TAM for more than 1.52 years.