Prioritize cardiac monitoring for high-risk breast cancer patients, study suggests

Cardiac monitoring should be a priority among trastuzumab-treated high-risk patients, patients with comorbidities, and those treated with anthracyclines.

Heart failure risk is higher in breast cancer patients treated with certain types of chemotherapy and lower in younger patients, a study found.

To study the rate of chemotherapy-related cardiotoxicity and the rate of cardiac monitoring adherence among breast cancer patients, researchers recruited 16,456 patients 18 years and older (median age, 56 years) with a diagnosis of nonmetastatic invasive breast cancer between 2009 and 2014 who were treated with chemotherapy within six months of their diagnosis. Cardiotoxicity was defined as an incident case of heart failure following a breast cancer diagnosis.

The study appeared in the August JACC: Cardiovascular Imaging.

Cardiotoxicity occurred in 4.2% of patients. There was an increased risk of cardiotoxicity in patients treated with trastuzumab (hazard ratio [HR], 2.01; 95% CI, 1.72 to 2.36) and in those treated with anthracyclines (HR, 1.53; 95% CI, 1.30 to 1.80). Risk was also increased in patients with a Deyo comorbidity score of 1 (HR, 1.38; 95% CI, 1.15 to 1.66), a Deyo comorbidity score of 2 or greater (HR, 2.47; 95% CI, 1.94 to 3.15), hypertension (HR, 1.28; 95% CI, 1.09 to 1.51), and valve disease (HR, 1.93; 95% CI, 1.48 to 2.51). (The Deyo comorbidity score is an index that assigns a score to various chronic medical conditions and uses the sum to predict long-term mortality, with a higher score representing greater risk.)

Patients ages 35 years or younger (HR, 0.37; 95% CI, 0.19 to 0.72) and ages 36 to 49 years (HR, 0.49; 95% CI, 0.38 to 0.62) were less likely to have cardiotoxicity than patients 65 years of age and older. Among the 4,325 patients treated with trastuzumab, 46.2% received guideline-adherent cardiac monitoring. Patients who received anthracyclines (odds ratio [OR], 1.58; 95% CI, 1.35 to 1.87), taxanes (OR, 1.63; 95% CI, 1.27 to 2.08), or radiation (OR, 1.22; 95% CI, 1.08 to 1.39) were more likely to also receive guideline-adherent monitoring.

The researchers said there could be many explanations for the low rates of cardiac monitoring seen in the patients treated with trastuzumab, including a low perceived need on the part of the physicians, rather than an unawareness of the guidelines. They concluded that cardiac monitoring should be a priority among trastuzumab-treated, high-risk patients, as well as among patients with comorbidities or those treated with anthracyclines.

“Biomarkers may be promising and cost effective in the prediction of cardiotoxicity compared to cardiac monitoring,” they wrote. “The number of cancer survivors is expected to increase over time, and we will continue to see patients develop treatment-related cardiotoxicity. Thus, more research, evidence-based guidelines, and tools for prediction of cancer treatment-related cardiotoxicity are needed.”

An editorial noted that the FDA, medical societies, and clinical practice guidelines recommend left ventricular ejection fraction monitoring every three months in patients taking adjuvant trastuzumab therapy. However, rates of adherence to these guidelines have been low in clinical practice.

“[S]trong collaboration between our cardiology and oncology communities is critical as we aim to optimally treat patients with the most effective cancer therapy, with minimal interruption, while achieving the best short- and long-term cardiac outcomes,” the editorial stated.