A. Jo Chien, MD, Associate Professor at UCSF’s Helen Diller Comprehensive Cancer Center, San Francisco, was the formal discussant of this abstract. Dr. Chien said that a median follow-up of 3-years is relatively short for this trial, considering about 75% of patients had hormone receptor–positive breast cancer, and recurrences are more common with longer follow-up in that group of patients. “Due to the high rates of discontinuation in the T-DM1 arm, it is important to remember that the duration of toxicity is a contributor to overall tolerability, which often is not well characterized by standard toxicity assessments that often just report highest-grade toxicity at one point in time,” she continued. “High-grade toxicities that are short-lived may be acceptable [to patients], but low-grade toxicities for longer duration may not.”

According to Dr. Chien, some low-grade toxicities may have a greater impact on patients’ well-being. Thus, she noted, treatment should be individualized, taking patients’ circumstances and preferences into account. 

DISCLOSURE: Dr. Chien has received institutional research funding from Merck, Puma, Seattle Genetics, Astellas, and Amgen.