MRI surveillance without prophylactic cranial irradiation improved cognitive failure-free survival and substantially reduced serious treatment-related adverse events

SEOUL, Republic of Korea, Sept. 13, 2026 /PRNewswire/ -- Results from the international phase III SWOG S1827 MAVERICK trial show that brain MRI surveillance alone improved cognitive failure-free survival compared with MRI surveillance plus prophylactic cranial irradiation (PCI) in patients with small-cell lung cancer (SCLC). The findings support MRI surveillance alone as the standard of care for patients with SCLC, according to research presented at the International Association for the Study of Lung Cancer (IASLC) 2026 World Conference on Lung Cancer (WCLC).

For decades, PCI has been used after initial therapy for SCLC because studies conducted before routine MRI demonstrated that it reduced brain metastases and improved overall survival. MAVERICK was designed to determine whether modern MRI surveillance could allow patients to avoid PCI—and its potential cognitive and other toxicities—without compromising survival.

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 MRI surveillance alone or MRI surveillance plus PCI (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 study's cognitive assessments included the Hopkins Verbal Learning Test-Revised, Controlled Oral Word Association and Trail Making Test.

At a median follow up of 22 months among living patients, MRI surveillance alone significantly improved cognitive failure-free survival, the trial's primary endpoint, reducing the risk of cognitive failure or death by 40% compared with MRI plus PCI (HR 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.

A preliminary overall survival analysis, conducted after 128 deaths, showed no apparent difference between the treatment strategies (HR for the MRI alone arm, 0.90; 90% CI 0.67–1.20). The final overall survival analysis is planned after 190 deaths. Brain metastasis-free survival also was not significantly different between the two groups (HR 1.25; 90% CI 0.95–1.66).

Serious treatment-related adverse events were 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.

"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."

About the IASLC

The International Association for the Study of Lung Cancer (IASLC) is the only global organization dedicated solely to the study of lung cancer and other thoracic malignancies. Founded in 1974, the association's membership includes more than 10,000 lung cancer specialists across all disciplines in over 100 countries, forming a global network working together to conquer lung and thoracic cancers worldwide. The association also publishes the Journal of Thoracic Oncology, the primary educational and informational publication for topics relevant to the prevention, detection, diagnosis, and treatment of all thoracic malignancies. Visit www.iaslc.org for more information.

About the WCLC

The WCLC is the world's largest meeting dedicated to lung cancer and other thoracic malignancies, attracting nearly 7,000 researchers, physicians, and specialists from more than 100 countries. The goal is to increase awareness, collaboration and understanding of lung cancer, and to help participants implement the latest developments across the globe. The conference will cover a wide range of disciplines and unveil several research studies and clinical trial results. For more information, visit https://wclc.iaslc.org/.

Contact: Chris Martin, IASLC Media Relations, cmartin@davidjamesgroup.com 

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SOURCE International Association for the Study of Lung Cancer