Study shows estrogen blocker treatment does not increase risk of coronary heart disease in breast cancer patients

New evidence shows that extended estrogen suppression treatment using aromatase inhibitors for hormone receptor-positive postmenopausal breast cancer is safe; it does not increase the risk of coronary artery calcification, a sign of active coronary atherosclerosis, as some prior studies had indicated.

An article in the Canadian Journal of Cardiology details the findings from a retrospective, cross-sectional observational study that investigated the association between the duration of aromatase inhibitor treatment and the severity of coronary artery calcification in postoperative breast cancer patients.

Coronary artery calcification is a significant predictor of adverse outcomes in the general population, which is believed to be associated with atherosclerosis, the condition that causes angina and heart attacks. Despite estrogen’s beneficial role in cardiovascular health, its suppression is often necessary in patients with breast cancer.

Hormonal therapy, particularly the use of aromatase inhibitors (which block the production of estrogen), is a standard treatment after breast cancer surgery for postmenopausal women. While these therapies are effective in reducing cancer recurrence, there is increasing concern about their potential cardiovascular side effects, including acceleration of coronary artery atherosclerosis.

Lead investigator Yu Hiasa, MD, Department of Cardiology, Pulmonology, Hypertension & Nephrology, Ehime University Graduate School of Medicine, Toon, Japan, explains, “Although there is an ongoing discussion on the optimal duration of aromatase inhibitor therapy (five years or 10 years), our data suggest that longer aromatase inhibitor use (as often used to prevent or suppress late recurrences or spread of breast cancer) is safe, at least in regard to coronary artery calcification.”

The investigators conducted a single-center, retrospective, cross-sectional observational study among 357 postmenopausal breast cancer patients who initiated adjuvant endocrine therapy with aromatase inhibitors for breast cancer between August 2010 and October 2022 as outpatients.

Coronary artery calcification was quantified using a visual ordinal scoring system, and patient characteristics were assessed based on the presence of coronary artery calcification. Independent risk factors for elevated coronary artery calcification scores were identified through a multivariable logistic regression model.

Co-investigator Akinori Higaki, MD, Ph.D., Department of Cardiology, Pulmonology, Hypertension & Nephrology, Ehime University Graduate School of Medicine, Toon, Japan, adds, “Our analysis of the postoperative breast cancer patient cohort revealed that the duration of treatment with aromatase inhibitors and the presence of osteoporosis were not associated with coronary artery calcification.”

In patients diagnosed with coronary artery calcification prior to the study, its severity was not impacted by the treatment.

In addition to the well-known risk factors for coronary artery calcification such as older age, hypertension, and diabetes mellitus, researchers found that a lower hemoglobin level is also an independent risk factor for coronary artery calcification.

In an accompanying editorial, Ibrahim Alfaris, MBBS, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, notes, “Identifying low hemoglobin as a novel, highly significant risk factor for coronary artery calcification in this population raises the possibility of adding anemia as an indication for cardiovascular screening.

“Anemia is not typically noted in classic atherosclerotic cardiovascular disease risk calculators or expert recommendations, and this finding could lead to changes in screening practices for postmenopausal women undergoing aromatase inhibitor therapy.”

Dr. Alfaris concludes, “Understanding the association between the duration of aromatase inhibitors treatment and the severity of coronary artery calcification in postoperative breast cancer patients is crucial, as it impacts the long-term health management of breast cancer survivors, who are at significant risk for cardiovascular disease due to the anti-estrogenic effects of their therapy.”