Toon, Japan—Pharmacists often hear concerns from breast cancer patients about the risks of estrogen-blocker treatment. A new study has recently found that aromatase inhibitors do not appear to increase the risk of coronary heart disease.

The report in the Canadian Journal of Cardiology offers new evidence that extended estrogen-suppression treatment using aromatase inhibitors for hormone receptor-positive postmenopausal breast cancer is safe. The treatment did not appear to increase the risk of coronary artery calcification, a sign of active coronary atherosclerosis, as some prior studies had indicated, according to the researchers.

The 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 was conducted by Japanese researchers from Ehime University Graduate School of Medicine.

The articles pointed out that coronary artery calcification is a significant predictor of adverse outcomes in the general population and is believed to be associated with atherosclerosis, the condition that causes angina and heart attacks. The suppression of estrogen is a standard treatment after breast cancer surgery for postmenopausal women. The therapies are effective in reducing cancer recurrence, but concerns have been raised about their potential cardiovascular side effects, including acceleration of coronary artery atherosclerosis.

Lead investigator Yu Hiasa, MD, explained, “Although there is an ongoing discussion on the optimal duration of aromatase inhibitor therapy (5 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.”

To reach those conclusions, 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 as outpatients for breast cancer between August 2010 and October 2022. 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.

In addition, in patients diagnosed with coronary artery calcification prior to the study, the severity was not impacted by the treatment. The researchers also found that a lower hemoglobin level is an independent risk factor for coronary artery calcification in addition to the well-known risk factors for coronary artery calcification, such as older age, hypertension, and diabetes mellitus.

In an accompanying editorial, Ibrahim Alfaris, MBBS, division of cardiovascular medicine at Stanford University School of Medicine, wrote, “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 inhibitors therapy.”

Dr. Alfaris also suggested, “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.”

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