MRI Monitoring Alone Preserves Cognitive Function Better Than Preventive Brain Radiation in Lung Cancer

A phase III trial found that patients with small cell lung cancer who underwent only MRI surveillance had better cognitive failure-free survival than those who also received prophylactic cranial irradiation, with 6-month rates of 38% versus 17%. No significant difference in overall survival was seen between the two strategies in an interim analysis. The results suggest MRI surveillance may be the preferred approach, though final survival data from ongoing trials are awaited for limited-stage disease.

The MAVERICK trial enrolled 304 patients with both limited- and extensive-stage SCLC, with a median age of roughly 66–67 years and about two-thirds presenting with limited-stage disease. Participants underwent brain MRI scans every three months during the first year and every six months during the second, alongside cognitive testing using instruments such as the Hopkins Verbal Learning Test-Revised and Trail Making Test. The trial was amended to elevate cognitive failure-free survival to the primary endpoint after accrual rates fell short of projections.

PCI has historically reduced intracranial progression by roughly half, but concerns about cognitive toxicity have grown since routine MRI surveillance became standard. The PRIMALung trial is now testing whether MRI surveillance alone is noninferior to PCI plus surveillance for overall survival, and final survival results from MAVERICK are still pending.