Trastuzumab can improve disease-free survival (DFS) and overall survival (OS) in patients with human epidermal growth factor receptor 2-positive (HER2+) breast cancer. Although some studies suggest that short-term treatment (less than one year) may reduce cardiac toxicity and cost without compromising outcomes, the results of a new study presented at the San Antonio Breast Cancer Symposium on December 8, 2018, disagree.

Investigators systematically searched PubMed, EMBASE, Cochrane Library, Google Scholar Web, Institute for Scientific Information’s Web of Science, BIOSIS, China Academic Journals database, and major conference abstracts in June 2018 to identify five noninferiority studies comparing short- and long-term adjuvant trastuzumab. The studies included 11,376 women with HER2+ breast cancer, of whom 5,684 received short-term treatment and 5,692 received one-year treatment.

Women receiving the shorter course of trastuzumab had a worsening trend of DFS (hazard ratio [HR] = 1.19; 95% confidence interval [CI] = 1.08–1.30) and OS (HR = 1.22; 95% CI = 1.07–1.39) compared to those receiving the one-year course.

A subgroup analysis assessed subtype-related treatment outcomes but found no statistical interaction associated with estrogen receptor (p = 0.12) and lymph node (p = 0.52) status.

Patients receiving short-term trastuzumab experienced statistically significantly less cardiotoxicities (odds ratio = 0.54; 95% CI = 0.38–0.77).

“One-year adjuvant trastuzumab remains the standard strategy for HER2+ early breast cancer; however, a concomitant higher risk of associated cardiac adverse effects should not be ignored,” the researchers concluded.