SAN ANTONIO – A phase 3 randomized NRG Oncology trial (NSABP B-39/RTOG 0413) was unable to rule out the possibility that, after lumpectomy, partial breast irradiation is inferior to whole breast irradiation when it comes to the ipsilateral breast tumor recurrences (invasive disease or ductal carcinoma in situ), reported Frank Vicini, MD, of MHP Radiation Oncology Institute, Pontiac, Mich.
The hazard ratio for this event with the former versus latter modality was 1.22, with the 90% confidence interval (0.94-1.58) falling just outside the predefined range to declare the two modalities equivalent (0.667-1.5). However, the absolute difference in the 10-year cumulative incidence of ipsilateral breast tumor recurrences was just 0.7% (4.6% vs. 3.9%). In a video interview, Dr. Vicini discussed whether this difference is clinically important, and the implications of the trial’s findings, taken together, for offering partial breast irradiation to patients.
Dr. Vicini disclosed that he is a research adviser for ImpediMed. The study was sponsored by the National Cancer Institute.