Kristin Higgins, MD

The discussant of the abstract on the use of prophylactic cranial irradiation in patients with extensive-stage small-cell lung cancer (SCLC), Kristin Higgins, MD, underscored the marked shift in practice patterns in the United States. However, she noted that many questions remain concerning prophylactic cranial irradiation. Dr. Higgins is Associate Professor of Radiation Oncology at Winship Cancer Institute of Emory University, Atlanta.

“In the extensive-stage SCLC setting, Americans are now shifting toward the Japanese approach versus the European approach,” revealed Dr. Higgins. “One question that hasn’t been answered, however, is whether patients being offered prophylactic cranial irradiation are undergoing surveillance with magnetic resonance imaging (MRI) every 3 months as well. I think in practice, it’s probably heterogeneous.”

“Interestingly,” Dr. Higgins added, “the majority of survey respondents were willing to support an MRI surveillance trial in both extensive-stage and limited-stage populations. This is surprising given that the role of prophylactic cranial irradiation in limited-stage disease is well supported with survival data.”

Mitigating Toxicity With Cranial Irradiation

There are new approaches for mitigating toxicity with prophylactic cranial irradiation, including hippocampal avoidance, noted Dr. Higgins. An ongoing NRG Oncology study (NRG-CC003) has randomly assigned patients with both limited-stage and extensive-stage SCLC to receive prophylactic cranial irradiation with the standard approach vs prophylactic cranial irradiation with intensity-modulated radiation therapy. The study is currently enrolling patients.

Emerging Role of Immunotherapy

According to Dr. Higgins, an additional question for extensive-stage disease involves how prophylactic cranial irradiation fits into the new standard of care, given results from the IMpower133 trial. In this trial, improvements in progression-free and overall survival were shown when atezolizumab was added to first-line chemotherapy.¹

“In this trial, 10% of patients received prophylactic cranial irradiation, and there were no worrisome toxicities,” said Dr. Higgins. “Although we haven’t seen any pattern of failure data, we know from the PACIFIC study that patients who received immunotherapy had significantly less failure in the brain. It will be interesting to see whether this pans out in the small cell setting.” ■

DISCLOSURE: Dr. Higgins is a consultant for AstraZeneca and Varian, is on the advisory board for Genentech and AstraZeneca, and has received research funding from RefleXion Medical.

REFERENCE

1. Horn L, Mansfield AS, Szczesna A, et al: First-line atezolizumab plus chemotherapy in extensive-stage small-cell lung cancer. N Engl J Med 379:2220-2229, 2018.