Cardiac Function Checkup During Trastuzumab Therapy Among Patients With Breast Cancer

Appropriate cardiac function evaluation before trastuzumab therapy is recommended. However, there are no data that show the current practice of appropriate cardiac evaluation for patients receiving postsurgical adjuvant trastuzumab (adjuvant group) and patients with metastatic disease (metastatic group).

We assessed patients with newly diagnosed breast cancer who received trastuzumab between October 2011 and December 2016 using the national database of the Hospital-Based Cancer Registry. We defined appropriate cardiac function checkup as having ultrasound echocardiogram (UCG) before the start of trastuzumab as well as within 6 months after trastuzumab initiation for the adjuvant group, and having UCG before trastuzumab for the metastatic group.

In the adjuvant group (14,501 patients), 34.7% of patients received appropriate UCG checkup. Factors related to appropriate UCG were 65 years or older (OR 1.54, 95% CI 1.41-1.69), advanced stage (stage II OR 1.18, 95% CI 1.07-1.30, stage III OR 1.08, 95% CI 0.96-1.23 compared to stage I), and surgical department (OR 0.57, 95% CI 0.47-0.70). In the metastatic group (1734 patients), appropriate UCG checkup was performed in 72.1% of the patients. Factors associated with appropriate UCG included 65 years or older (OR 1.45, 95% CI 1.10-1.91) and anthracycline use before trastuzumab (OR 0.59, 95% CI 0.44-0.80). UCG checkup rate improved from 2012 to 2015 in both the adjuvant and metastatic groups.

Although many patients still received suboptimal UCG checkup, it has been improving over time. The level of appropriate UCG checkup was different between physicians with different specialties.