Treatment with aromatase inhibitors did not correspond to an excess rate of ischemic cardiotoxicity in postmenopausal patients with early breast cancer, regardless of cardiovascular disease history, according to study results published in The Lancet Oncology.

Aromatase inhibitors are the preferred endocrine treatment for postmenopausal patients with ER-positive early breast cancer. However, the relationship between aromatase inhibitor therapy and the risk for ischemic cardiotoxicity remains unclear.

Researchers in Denmark identified patients with breast cancer in the Danish Breast Cancer Cooperative Group clinical database who were diagnosed between 2009 and 2020. This registry study included patients assigned to aromatase inhibitors and a non-tamoxifen control group.

The study included data from 32,635 patients, of whom 29,118 had no history of selected cardiovascular disease. In this cohort, 22,135 patients were assigned to aromatase inhibitors and 6,938 were assigned to the control group.

The researchers observed 510 two-point major adverse cardiovascular events among those assigned to aromatase inhibitors, compared with 170 two-point major adverse cardiovascular events among those who were not. The incidence rates were 4.3 per 1000 person-years and 4.1 per 1000 person-years, respectively (adjusted hazard ratio [HR] = 0.91; 95% CI, 0.73-1.14).

The researchers also included 3,517 patients with a history of cardiovascular disease, of whom 2,661 were assigned to aromatase inhibitors. They observed 158 two-point major adverse cardiovascular events among patients assigned to aromatase inhibitors and 50 two-point major adverse cardiovascular events among those not assigned to aromatase inhibitors.

In a post hoc analysis, the researchers observed an increased risk for heart failure among patients with a history of selected cardiovascular disease who were assigned to aromatase inhibitors (adjusted HR = 1.6; 95% CI, 1.01-2.54).

“Concerns about ischemic cardiotoxicity should not prevent treatment with aromatase inhibitors in patients with and without previous ischemic cardiovascular disease. Further investigations are needed to clarify whether there is an increased risk of our secondary outcome, heart failure. However, if real, that risk should be balanced against the reduced breast cancer recurrence and mortality rates of treatment with aromatase inhibitors compared with tamoxifen,” Marie Lund, PhD, of the Department of Clinical Medicine, Faculty of Health and Medical Sciences at University of Copenhagen, and colleagues wrote.

Reference:
https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(24)00491-1/abstract

Disclosures: Some researchers declared financial ties to drugmakers. See full study for details.

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