Pulsed Reduced-Dose Rate Re-Irradiation With Intensity Modulated Radiation Therapy (IMRT) for Recurrent Primary Central Nervous System Malignancies.

Abstract

PURPOSE/OBJECTIVE(S)\nPulsed Reduced-Dose Rate (PRDR) Re-irradiation with Intensity Modulated Radiation Therapy (IMRT) for recurrent primary Central Nervous System (CNS) malignancies was previously reported to be a feasible and well tolerated treatment option. We report our IMRT PRDR outcomes and toxicities for 55 patients with KPS ≥ 70 treated at our institution.\n\n\nMATERIALS/METHODS\nWe did a retrospective review of our database of 55 patients with recurrent primary CNS tumors treated at our institution treated with PRDR IMRT. Data collected included demographic information, initial diagnosis, prior surgery, radiation, and chemotherapy, toxicities for each treatment, PRDR IMRT plans, dates of progression, and date of death when available.\n\n\nRESULTS\nThe mean age of our patient population at diagnosis was 40.2 years. 31 patients were male and 24 patients were female. The initial diagnosis was WHO grade IV in 16 patients, 12 grade III, 21 Grade II, 1 Grade I glioma, and 5 patients had other primary CNS malignancies. All patients had at least 1 surgery (range 1-5) followed by initial radiation. The mean number of salvage treatments undergone by our cohort before PRDR IMRT was 2.83 treatments. The mean dose of prior radiation therapy was 57.75 Gy (Range 50.4 Gy to 75 Gy). Mean Karnofsky Performance Status (KPS) at PRDR IMRT was 80. 14 patients had an updated pathologic diagnosis before PRDR; 6 of those had grade III gliomas and 8 had grade IV. The average time from the first radiation treatment to the PRDR was 68.6 months. The dose of PRDR given ranged from 50.4 Gy to 60 Gy at 1.8-2 Gy/fraction (Median 54 Gy in 30 fractions, with one exception of a patient who stopped early). The mean progression free survival (PFS) after PRDR IMRT was 5.59 months. The median PFS was 4.8 months. Overall Survival (OS) from the time of initiation of PRDR was 10.98 months. The treatment was well tolerated with 86.6% of adverse events being grade 1-2. There were 3 grade 3 adverse events and 3 grade 4 side effects all attributed to concurrent chemotherapy. There was no radiation necrosis reported after PRDR IMRT.\n\n\nCONCLUSION\nWe report a large institutional series of patients who were treated with PRDR IMRT for recurrent primary CNS malignancies. Our series shows the feasibility, safety and efficacy of PRDR IMRT for re-irradiation for recurrent primary CNS malignancies in our heavily pretreated population with a good performance status. This warrants further prospective studies of PRDR IMRT in a randomized setting.\n\n\nAUTHOR DISCLOSURE\nA. Halima: None. S.T. Chao: Honoraria; Varian Medical Systems, Zeiss, AbbVie. Consultant; AbbVie. J.H. Suh: Consultant; Philips, Novocure. Met to discuss current indications for TTF; Novocure. Met during 1 day retreat to discuss future of radiation oncology; Philips. Scientific advisory board; Neutron Therapeutics. J.S. Yu: None. T.A. Chan: None. S.S. Kilic: None. D. Peereboom: None. G. Stevens: None. Y. Rauf: None. E.S. Murphy: None.