Radiographic response to first-line treatment tied to longer survival in HER2-positive breast cancer

Patients with de novo human epidermal growth receptor 2 (HER2)-positive metastatic breast cancer (MBC) who show radiographic response to first-line HER2-directed therapy are more likely to achieve long-term survival, suggests a recent study.

Using the Manitoba Cancer Registry, a team of investigators identified eligible patients with de novo HER2-positive MBC from 2008 to 2018. They used univariate logistic regression models to examine the variables of clinical interest and the chances of long-term survival, defined as survival ≥5 years from the time of diagnosis.

The investigators also used the Kaplan-Meier method, with log-rank comparative analyses as a univariate analysis, to estimate the overall survival (OS), defined as the time from diagnosis of MBC to death of any cause. They then used a Cox proportional hazards model for OS estimates in a univariate analysis.

Of the 62 patients who had a diagnosis of de novo HER2-positive MBC and received HER2-directed therapy, 18 (29 percent) achieved LTS.

The entire cohort had a median OS of 50.2 months (95 percent confidence interval [CI], 28.6‒not reached). Radiographic response to first-line treatment was predictive of long-term survival, while complete (odds ratio [OR], 28.33, 95 percent CI, 2.47‒4,006.71; p=0.0043) and partial responses (OR, 7.80, 95 percent CI, 0.7317‒1,072.00; p=0.0972) correlated with higher chances of long-term survival.

In addition, the best radiographic response significantly correlated with improved OS.

“Larger studies are needed to identify patients who can safely discontinue HER2-targeted therapy,” the investigators said.

“Although MBC is considered incurable, HER2-directed therapy has improved outcomes significantly, with some patients experiencing durable responses to treatment,” they noted.