Thomas Buchholz, MD, of the University of Texas MD Anderson Cancer Center, Houston, commented that the “well conducted and analyzed” MA.20 study addressed a “simple clinically relevant question,” and the findings “add to the conclusive evidence that radiation eradication of local-regional microscopic disease reduces subsequent distant metastases and can improve survival.”

He said the locoregional results are not surprising, as outcomes were consistent with expectations. “A 5.5% locoregional recurrence rate at 5 years is expected, and the 2.3% absolute improvement is reasonable,” he noted. “By itself, the locoregional benefit and risks are equal.”

But he found the 4.3% absolute reduction (from 12.7% to 8.4%) in distant metastases “surprising,” and suggested that based on these data, “the benefits now clearly outweigh the risks.” While surprising, there are a number of possible reasons why protection from distant metastases was greater than for locoregional recurrences, but what seems certain is that lymph node risk is heterogeneous within the subset of patients with one to three positive nodes, Dr. Buchholz offered.

“I agree with the investigators’ conclusions,” he said. “We should offer regional nodal irradiation for higher-risk patients with one to three positive lymph nodes, but we should await additional data for low-risk patients with one to three positive nodes.” ■

Disclosure: Dr. Buchholz reported no potential conflicts of interest.