RT Journal Article SR Electronic T1 Stereotactic and Hypofractionated Radiotherapy Associated With Immune Checkpoint Inhibitor Drugs: Analysis of Local Control, Toxicity, and Outcome in a Single Research Centre Case Study JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 5107 OP 5116 DO 10.21873/anticanres.15327 VO 41 IS 10 A1 DIMITRI ANZELLINI A1 VITALIANA DE SANCTIS A1 MAURIZIO VALERIANI A1 CHIARA REVERBERI A1 LUCA MARINELLI A1 MARIA MASSARO A1 GIANLUCA VULLO A1 GIUSEPPE FACONDO A1 RICCARDO CARLO SIGILLO A1 EMANUELE TOSI A1 MATTIA FALCHETTO OSTI YR 2021 UL http://ar.iiarjournals.org/content/41/10/5107.abstract AB Background/Aim: We evaluated local control and toxicity in patients receiving radiotherapy associated with immune check point inhibitors and analyzed which oligometastatic disease setting benefits the most from local ablation in terms of advantage in overall survival. Patients and Methods: We retrospectively identified 60 oligoprogressive patients treated with a PD-1 inhibitor in association with radiotherapy on the site of progression (119 lesions). Results: After a median follow-up of 11.7 months (range=1-39 months), we observed complete response (CR) in 45/119, partial response (RP) in 42/119, and stable disease (SD) in 30/119 patients. Nine radionecrotic events occurred. Two patients experienced grade 3 toxicities and 32 patients reported grade 2 toxicities. The number of radiologically evident metastatic organs in patients who received concomitant PD-1 inhibitors and radiotherapy showed a significant increase in survival (respectively, 73% after 12 months and 47% after 24 months) in patients with 0-3 metastatic organs compared to those with more than 3 organ sites involved (p<0.0001). Conclusion: Radiotherapy associated with PD-1 inhibitors is overall safe and efficacious. Patients eligible for intensification of local treatments should have less or equal to 3 metastatic organ sites.