Histopathologically confirmed radiation necrosis: Risk factors and clinical outcomes in patients with primary brain tumors.

Background: Radiation necrosis is a recognized complication following radiotherapy for primary brain tumors, presenting diagnostic and therapeutic challenges, and potentially masquerading as tumor recurrence. This study aims to delineate the clinical trajectory, management strategies, and outcomes of histologically confirmed radiation necrosis in patients treated for primary brain tumors.

Methods: We conducted a retrospective review of patients who underwent surgical intervention for suspected tumor recurrence at our institution between 2010 and 2022, following adjuvant radiotherapy. Cases with histopathologically confirmed radiation necrosis were identified and analyzed for onset, clinical symptoms, radiological features, correlation with radio- and chemotherapy, management approaches, and disease progression.

Results: Out of 276 patients operated for suspected recurrent brain tumors, 14 (5%) were histopathologically diagnosed with radiation necrosis. The latency period from radiotherapy to diagnosis ranged from 3 to 40 months. Notably, patients with oligodendrogliomas exhibited a significantly higher incidence of radiation necrosis (26%), underscoring a substantial risk association (P < 0.001). Conversely, the rates of radiation necrosis in patients with glioblastoma and astrocytoma (WHO grade II and III) were lower, at 2% and 0%, respectively, suggesting a lower risk association (P < 0.001 and P = 0.036, respectively). The majority (79%) of these patients were asymptomatic and exhibited a favorable clinical course, with most cases showing no progression of necrosis. During the follow-up period, tumor recurrence was verified in 2 patients.

Conclusion: Radiation necrosis post-radiotherapy for primary brain tumors occurs infrequently but predominantly in patients with oligodendrogliomas, often following a benign course. The study underscores the importance of close monitoring for this condition, given the potential for sampling errors and the critical need for histopathological confirmation to guide appropriate management.