Randomized trial of medroxyprogesterone acetate for the prevention of endometrial pathology from adjuvant tamoxifen for breast cancer: SWOG S9630

Prospective Exploratory Study of the Effects of Postoperative Endocrine Medication on the Endometrium in Breast Cancer Patients

Objective

This study aimed to investigate the pathological effects of long-term postoperative endocrine medication on the endometrium in breast cancer patients.

Methods

Data of 99 patients with primary breast cancer who underwent hysteroscopy and obtained endometrial biopsy from 1 June 2018 to 31 December 2021 at the Beijing Obstetrics and Gynecology Hospital, Capital Medical University. Beijing Maternal and Child Health Care Hospital were prospectively collected.

Results

Hysteroscopy was performed followed by endometrial histopathological examination in 99 breast cancer patients, including 44 taking tamoxifen (TAM), 26 taking other endocrine drugs, and 29 not taking endocrine drugs. The endometrial thickness in the TAM group was significantly higher than that in the other endocrine drug groups and the group not taking endocrine drugs (p=0.017). The receiver operating characteristic curves for the abnormal premenopausal endometrial thickening were plotted in this study; an endometrial thickness of 15.5 mm seen on ultrasound could be used as the most accurate ultrasound diagnostic threshold for the diagnosis of abnormal premenopausal endometrial hyperplasia, with an area under the curve of 0.888 (95% CI: 0.716, 1.000), a sensitivity of 100%, and a specificity of 75%, which was consistent with the results of our previous retrospective study. An endometrial thickness of ≥5 mm in postmenopausal women with breast cancer taking TAM was still used as the cut-off value for routine ultrasound diagnosis of abnormal postmenopausal endometrial hyperplasia.

Conclusion

An ultrasound endometrial thickness (proliferative phase) of >15 mm in premenopausal patients can be used as the most accurate ultrasound diagnostic threshold for the diagnosis of abnormal endometrial hyperplasia. After menopause, an ultrasound endometrial thickness of ≥5 mm is still used as the criterion for diagnosing abnormal endometrial hyperplasia. Older patients should be monitored for signs of vaginal bleeding and fluid discharge, and hysteroscopy should be performed if necessary to ascertain the endometrial condition.

Tamoxifen and Endometrial Cancer: A Janus-Headed Drug

Simple Summary

Tamoxifen, an antiestrogen, is a potent drug to treat and prevent hormone dependent breast cancer. As it has low toxicity and is widely available, tamoxifen has become one of the most frequently prescribed anticancer drugs worldwide. A major side effect of tamoxifen is to increase the risk of uterine corpus cancer (endometrial cancer). This happens after long-term (>2 years) application, especially in postmenopausal women with preexisting pathologies in the uterus. On the other hand, tamoxifen is an efficacious treatment for certain forms of advanced endometrial cancer, thus making it a Janus-headed drug that can support the development of endometrial cancer on one hand and be used as a remedy for this disease on the other. This article reviews the clinical data on these controversial effects of tamoxifen and the possible explanations.

Abstract

Tamoxifen is a selective estrogen receptor modulator used for the treatment and prevention of estrogen receptor (ER)—positive breast cancer. However, tamoxifen increases the risk of endometrial cancer (EC) by about 2–7 fold, and more aggressive types of EC with poor prognoses are observed in tamoxifen users. On the other hand, tamoxifen is an efficacious treatment for advanced or recurrent EC with low toxicity. The differential agonistic or antagonistic effects of tamoxifen on ERα are explained by the tissue-specific expression profiles of co-activators and co-repressors of the receptor. The estrogen-agonistic effect of tamoxifen in endometrial cancers can also be explained by the expression of G-protein coupled estrogen receptor 1 (GPER-1), a membrane-bound estrogen receptor for which tamoxifen and other “antiestrogens” are pure agonists.

Celebrating an illustrious career in breast cancer research, SERMS and mentorship

V Craig Jordan speaks to Roshaine Wijayatunga, Managing Commissioning Editor: V Craig Jordan, OBE, PhD, DSc, MDhc, FMedSci, FAACR is Dallas/Ft Worth Living Legend Chair of Cancer Research, Professor of Breast Medical Oncology, Professor of Molecular and Cellular Oncology, and Chief, Section of Basic Science Research and Pharmacology. He trained as a pharmacologist at Leeds University Medical School and subsequently held Professorial appointments at the University of Wisconsin, Madison, Northwestern University, Chicago (Diana, Princess of Wales Professor of Cancer Research) and the Fox Chase Cancer Center, Philadelphia (the Alfred G Knudson Chair of Cancer Research). He was Professor of Oncology and Pharmacology at Georgetown University Medical Center and the Scientific Director of the Georgetown Lombardi Comprehensive Cancer Center, Washington, DC, USA. He developed the scientific principles for the effective use of tamoxifen, as an adjuvant therapy for breast cancer and the use of tamoxifen, as the first chemopreventive for breast cancer. His discovery and translational research of the novel group of medicines, known as Selected Estrogen Receptor Modulators, resulted in the development of raloxifene, for the prevention of osteoporosis and breast cancer. His contributions to medicine have been recognized with more than four dozen International Awards, including the Inaugural Brinker International Award (Susan G Komen for the Cure), David A Karnofsky Award (ASCO), the American Cancer Society (ACS) Medal of Honor, ACS Chemoprevention Prize (ASCO), the Charles F Kettering Prize and the St Gallen International Breast Cancer Prize. He is a Member of the National Academy of Sciences, a Fellow of the Academy of Medical Sciences and the National Academy of Medicine, and an Honorary Fellow of the Royal Society of Medicine. In 2002, he was appointed Officer of the Most Excellent Order of the British Empire, for services to International Breast Cancer Research.

How do we increase uptake of tamoxifen and other anti-estrogens for breast cancer prevention?

Several randomized controlled trials of anti-estrogens, such as tamoxifen and aromatase inhibitors, have demonstrated up to a 50–65% decrease in breast cancerincidence among high-risk women. Approximately 15% of women, age 35–79 years, in the U.S. meet criteria for breast cancer preventive therapies, but uptake of these medications remain low. Explanations for this low uptake includelack of awareness of breast cancer risk status, insufficient knowledge about breast cancer preventive therapies among patients and physicians, and toxicity concerns. Increasing acceptance of pharmacologic breast cancer prevention will require effective communication of breast cancer risk, accurate representation about the potential benefits and side effects of anti-estrogens, targeting-specific high-risk populations most likely to benefit from preventive therapy, and minimizing the side effects of current anti-estrogens with novel administration and dosing options. One strategy to improve the uptake of chemoprevention strategies is to consider lessons learned from the use of drugs to prevent other chronic conditions, such as cardiovascular disease. Enhancing uptake and adherence to anti-estrogens for primary prevention holds promise for significantly reducing breast cancer incidence, however, this will require a significant change in our current clinical practice and stronger advocacy and awareness at the national level.

The 4Ps of Breast Cancer Chemoprevention: Putting Proven Principles into Practice

The pioneering Royal Marsden Tamoxifen Prevention Trial recruited 2,471 eligible high-risk women to be randomized to either placebo or tamoxifen (20 mg daily) for 8 years. Breast cancer incidence was evaluated at a median of 18.4 years from the start of the study. There was a 32% reduction in estrogen/progesterone receptor (ER/PR)-positive breast cancers after tamoxifen treatment finished. Translational research, to study "the good, the bad, and the ugly of tamoxifen" in the 1980s, subsequently ensured women's safety from possible increases in osteoperosis, coronary heart disease, and endometrial cancer. Other tamoxifen chemoprevention trials followed. The result of laboratory research was the unanticipated discovery of raloxifene to prevent osteoporosis and breast cancer at the same time. A new group of medicines, now known as selective ER modulators, was established. Indeed, the ability to prevent or delay multiple diseases with a single cheap medicine has the potential to alleviate pressure on health care systems that are overwhelmed. It is a priority to educate physicians appropriately to apply recommended proven medicines as preventives. Cancer Prev Res; 10(4); 219-22. ©2017 AACRSee related article by Detre, et al., Cancer Prev Res 2017;10(3):171-6.