MRI Surveillance Alone Beats Preventive Brain Radiation in Small-Cell Lung Cancer Trial

Patients with small-cell lung cancer may be able to skip a decades-old radiation treatment to the brain without sacrificing survival, according to results from the international phase III SWOG S1827 MAVERICK trial presented at the International Association for the Study of Lung Cancer 2026 World Conference on Lung Cancer in Seoul. The trial found that brain MRI surveillance alone improved cognitive failure-free survival compared with MRI surveillance plus prophylactic cranial irradiation (PCI), and it substantially reduced serious treatment-related adverse events. The investigators say the findings support MRI surveillance alone as the standard of care for patients with SCLC.

For decades, PCI has been given after initial therapy for SCLC because studies conducted before routine MRI scanning demonstrated that it reduced brain metastases and improved overall survival. But the radiation has long carried a risk of cognitive and other toxicities. MAVERICK was designed to answer a modern question: whether regular MRI monitoring could allow patients to avoid PCI—and its potential cognitive harms—without compromising survival in an era when brain metastases can be detected early on imaging.

The trial enrolled 304 patients with limited-stage or extensive-stage SCLC between January 2020 and December 2025. All participants had completed initial therapy and had no brain metastases on MRI before enrollment. Patients were randomly assigned to one of two strategies: MRI surveillance alone, or MRI surveillance plus PCI delivered at a dose of 25 Gy in 10 fractions. In both groups, brain MRIs were performed every three months during the first year and every six months during the second year, with cognitive testing conducted at the same intervals.

The cognitive assessments used validated instruments, including the Hopkins Verbal Learning Test-Revised, the Controlled Oral Word Association test and the Trail Making Test. The trial’s primary endpoint, cognitive failure-free survival, combined cognitive decline and death into a single measure, allowing the study to capture the net effect of both the disease and the preventive treatment on patients’ brain function and survival.

At a median follow-up of 22 months among living patients, MRI surveillance alone significantly improved cognitive failure-free survival, reducing the risk of cognitive failure or death by 40% compared with MRI plus PCI (hazard ratio 0.60; 90% CI 0.46–0.78; p=0.001). The benefit was similar among patients with limited-stage and extensive-stage disease, and regardless of whether patients received immunotherapy, suggesting the advantage of avoiding PCI is consistent across major subgroups.

A preliminary overall survival analysis, conducted after 128 deaths, showed no apparent difference between the two strategies (hazard ratio for the MRI-alone arm, 0.90; 90% CI 0.67–1.20). The final overall survival analysis is planned after 190 deaths, so the survival picture is not yet final. Brain metastasis-free survival also was not significantly different between the groups (hazard ratio 1.25; 90% CI 0.95–1.66), indicating that skipping PCI did not clearly increase the risk of brain metastases appearing during surveillance.

Serious treatment-related adverse events were markedly less frequent with MRI surveillance alone. Grade 3–5 adverse events occurred in 0.8% of patients receiving MRI surveillance alone, compared with 7.9% of those receiving MRI plus PCI (p=0.004). One grade 5 encephalopathy event occurred in the MRI plus PCI group, underscoring that preventive brain radiation carries a small but real risk of severe neurological harm.

“MRI surveillance alone was associated with improved cognitive failure-free survival compared to a strategy of MRI surveillance plus PCI. The benefit of MRI surveillance alone also appears to be consistent across patients with both limited-stage and extensive-stage small-cell lung cancer,” said Chad Rusthoven, MD, of the University of Colorado School of Medicine and the study presenter. “These results support MRI surveillance alone as the standard of care for patients with SCLC.”

By pairing frequent MRI scans with structured cognitive testing at every interval, MAVERICK tested whether close monitoring could catch brain metastases early enough to preserve the survival benefit once attributed to prophylactic radiation, while sparing patients its cognitive costs.

If the planned final overall survival analysis confirms the preliminary findings, the trial could reshape routine practice for a disease in which preventive brain radiation has been a near-universal recommendation. For now, the phase III data indicate that for patients with SCLC who have completed initial therapy and show no brain metastases on MRI, surveillance with regular brain MRI alone delivered better cognitive outcomes with far fewer serious treatment-related adverse events than adding PCI.

Subject of Research: Whether brain MRI surveillance alone can replace prophylactic cranial irradiation after initial therapy for small-cell lung cancer

Article Title: Phase III MAVERICK trial supports brain MRI surveillance alone as standard of care for small-cell lung cancer

Article References: Phase III MAVERICK trial supports brain MRI surveillance alone as standard of care for small-cell lung cancer. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: small-cell lung cancer, MAVERICK trial, prophylactic cranial irradiation, brain MRI surveillance, cognitive failure-free survival, phase III trial, SWOG S1827, IASLC 2026 WCLC, adverse events, brain metastases, oncology, Phase