Elzbieta Senkus-Konefka, MD, PhD, of the Medical University of Gdansk, Poland, the formal discussant of the paper at the European Cancer Congress, took exception with the authors’ conclusion that radiotherapy may not be effective in all subtypes.

“I don’t agree that luminal B and HER2-enriched subtypes have no benefit,” Dr. Senkus-Konefka said, basing this conclusion largely on the small patient numbers. For example, in the HER2-enriched population, there was only one event seen in 10 patients in the radiotherapy arm. “You can’t draw conclusions from this,” she maintained.

The patients in these studies also received, by today’s practice, suboptimal systemic therapy, including no trastuzumab (Herceptin) for HER2-positive patients. “We know that systemic therapy improves local control, and we don’t know the effect of modern systemic therapies in these patients.”

Importance of Local Control

She also suggested that the largest benefit in the patients with the most favorable histology may partly be due to the relatively low risk of distant failure and proportionally larger effect of local control in this group. In other words, she said, “The largest benefit may be present in patients in whom the overall outcome is mostly determined by local control.”

The findings pose an interesting hypothesis, Dr. Senkus-Konefka concluded, “but this needs further study.”

Future research should evaluate gene expression in predicting locoregional control and benefit from postoperative radiotherapy in patients undergoing contemporary systemic treatment, with tailored patient selection. Other areas of research include the molecular prediction of tumor radiosensitivity and normal tissue tolerance and molecular prediction of tumor pattern spread, with radiotherapy technique and dose tailored, she suggested. ■

Disclosure: Dr. Senkus-Konefka reported no potential conflicts of interest.