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

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. 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. 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 ae 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. 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.