Tamoxifen-induced endometrial hyperplasia

Breast cancer is the most common cancer among the female population. In the adjuvant therapy regimens for hormone-sensitive breast cancer, tamoxifen is one of the most common and cost-effective drugs. Despite the fact that the main therapeutic effect of tamoxifen is associated with its antiestrogenic activity, the drug also acts as an agonist of estrogen receptors in other tissues of the body, such as the endometrium. Side effects of taking tamoxifen may include endometrial proliferation, hyperplasia, polyps, invasive carcinoma, and uterine sarcoma. An outpatient obstetrician-gynecologist most often encounters all these conditions. The main difficulty in managing such patients lies in the absence of uniform algorithms for assessing and further treatment tactics for patients taking tamoxifen, which often leads to unjustified drug withdrawal or numerous surgical manipulations.

The literature on the effect of tamoxifen on endometrial tissue and possible algorithms for the management of patients with hyperplastic processes during therapy were analyzed.

In the search databases such as Web of Science, eLibrary, Scopus, and PubMed / MEDLINE authors selected articles for the period 1991–2023 devoted to the assessment of the effect of tamoxifen on the endometrial condition using the following keywords: “tamoxifen”, “hyperplasia”, “breast cancer”, “endometrial cancer”, and “assessment”. No methodological filter was used to exclude the omission of suitable articles. This study included full-text sources and literature reviews on the subject under study. Articles that were not directly related to the topic of breast cancer therapy with tamoxifen were excluded from the review. To avoid including duplicate publications therein, if we found two studies by the same authors, the study period of each author was assessed, and if the dates coincided, we selected the most recent publication.

It can be concluded that there are restrictions on the management tactics of patients faced with endometrial hyperplastic processes while taking tamoxifen. Many patients included in existing studies and case reports have variable factors that make direct analysis or comparison complicated, such as age, the presence of hypertension, body mass index, various reproductive periods in which patients experienced breast cancer, the duration of tamoxifen intake, and the frequency of pelvic ultrasound. However, this literature review summarizes the data of recent major studies that may clarify the criteria for assessing endometrial thickness while taking tamoxifen and possible options for managing patients during breast cancer therapy.

The following steps can improve the quality of medical care for patients with hyperplasia during tamoxifen therapy: awareness of the patient about possible hyperplastic processes during therapy; awareness that any episode of abnormal uterine bleeding is a reason to see a doctor; pelvic ultrasound before starting tamoxifen therapy; the ultrasound thickness of the endometrium is not a reliable criterion, however, elastosonography may be a more promising technique for identifying the risks of malignancy.