SABCS 2018: Duration of Adjuvant Trastuzumab in Early Breast Cancer
Posted: Friday, December 7, 2018
The final analyses from the PHARE trial failed to show that 6 months of trastuzumab was noninferior to 12 months, suggesting that 12 months of adjuvant trastuzumab should remain the standard of care in patients with early HER2-positive breast cancer. Xavier Pivot, MD, PhD, of the Paul Strauss Cancer Center, Strasbourg, France, and colleagues presented their results at the 2018 San Antonio Breast Symposium (SABCS; Abstract GS2-07).
“The choice of the noninferiority margin will remain inherently a subject of controversy, especially in the context of oncology trials where the primary outcome is survival,” concluded the authors. As “the least additional death could be considered unacceptable,” they called into question “the very feasibility of such trials.”
In this phase III, multicenter, open-label, randomized study, patients with early HER2-positive breast cancer who had received prior breast-axillary surgery, chemotherapy, and trastuzumab were enrolled. A noninferiority margin of 1.15 was prespecified. Of the 3,380 patients who were evaluated, half received 12 months of trastuzumab, and half received 6 months.
The median follow up of the final analysis was 7.5 years. During this period, 704 events accounting for disease-free survival were recorded, and the adjusted hazard ratio was 1.08—in favor of 12 months of adjuvant trastuzumab. In terms of overall survival and metastasis-free survival, the adjusted hazard ratios were 1.13 and 1.15, respectively, again favoring longer exposure to trastuzumab.
