Does limited-margin radiotherapy change the recurrence pattern and survival of patients with high-grade gliomas? Analysis and validation of a different approach

Abstract

Purpose:We aimed to analyze our radiotherapy protocol by evaluating its effect on recurrence patterns and survival outcomes. Methods: We assessed 89 patients diagnosed with high-grade gliomas (HGGs) who underwent chemoradiotherapy at our institution from January 2014 to January 2021. A high-risk clinical target volume (CTV high) was created with a 1 cm margin in all directions from the GTV, while a low-risk clinical target volume (CTV low) was established with a 2 cm margin. Planned treatment volumes with a 2-3 mm margin in all directions were created, and doses of 60 Gy and 46-50 Gy were prescribed in 30 fractions. Recurrence patterns were classified as central, in-field, marginal, or distant based on the 60 and 50 Gy D95 isodose lines. Results: With a median follow-up of 29 months, 77.5% of patients experienced recurrence. Recurrence patterns were central in 65.2%, in-field in 16%, marginal in 4.3%, and distant in 14.5%. The overall survival rates at 1, 2, and 5 years were 87.6%, 60.3%, and 26.8%, respectively. The progression-free survival rates at the same intervals were 53.9%, 32.6%, and 20.7%, respectively. Conclusion: The recurrence pattern remained unchanged with our protocol. With longer survival times, distant recurrence rates increase, yet central and in-field recurrences remain dominant. Despite the decrease in the volume that received the 60 Gy dose, marginal recurrences remained at a notably low level.