Re-irradiation for recurrent glioma: outcome evaluation, toxicity and prognostic factors assessment. A multicenter study of the Radiation Oncology Italian Association (AIRO)

Introduction: The prognosis of glioma is dismal, and almost all patients relapsed. At recurrence time, several treatment options are considered, but to date there is no a standard of care. The Neurooncology Study Group of the Italian Association of Radiation Oncology (AIRO) collected clinical data regarding a large series of recurrent glioma patients who underwent re-irradiation (re-RT) in Italy. Methods: Data regarding 300 recurrent glioma patients treated from May 2002 to November 2017, were analyzed. All patients underwent re-RT. Surgical resection, followed by re-RT with concomitant and adjuvant chemotherapy was performed. Clinical outcome was evaluated by neurological examination and brain MRI performed, 1 month after radiation therapy and then every 3 months. Results: Re-irradiation was performed at a median interval time (IT) of 16 months from the first RT. Surgical resection before re-RT was performed in 19% of patients, concomitant temozolomide (TMZ) in 16.3%, and maintenance chemotherapy in 29%. Total doses ranged from 9 Gy to 52.5 Gy, with a median biological effective dose of 43 Gy. The median, 1, 2 year OS were 9.7 months, 41% and 17.7%. Low grade glioma histology (p ≪ 0.01), IT > 12 months (p = 0.001), KPS > 70 (p = 0.004), younger age (p = 0.001), high total doses delivered (p = 0.04), and combined treatment performed (p = 0.0008) were recorded as conditioning survival. Conclusion: our data underline re-RT as a safe and feasible treatment with limited rate of toxicity, and a combined ones as a better option for selected patients. The identification of a BED threshold able to obtain a greater benefit on OS, can help in designing future prospective studies.