Tumor return patterns after combined chemotherapy and radiotherapy in new glioblastoma patients linked to MGMT gene methylation

After a median follow-up of 18.9 months, 79 patients (83%) experienced recurrence following treatment for glioblastoma.

• Recurrences were most common inside the radiotherapy field, occurring in 57 patients (72.2%).
• Seventeen patients (21.5%) had recurrences outside the radiotherapy field, while five patients (6.3%) recurred at the margin.
• MGMT methylation status was correlated with the site of recurrence, with 85% of patients with unmethylated status experiencing recurrences inside or at the margin of the radiotherapy field compared to 57.9% of those with methylated status.
• Recurrences outside the radiotherapy field occurred after a longer interval (14.9 months) compared to those inside the field (9.2 months).

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