Evaluating the reduction of elective radiotherapy fields for de novo metastatic nasopharyngeal carcinoma in the immunotherapy era

Abstract Background This study evaluates the outcomes of omitting the high‐ and low‐risk clinical tumor volume (CTV1 and CTV2) radiation in de novo metastatic nasopharyngeal carcinoma (dnm‐NPC) patients in the immunotherapy era. Methods We retrospectively analyzed 45 consecutive dnm‐NPC patients receiving chemotherapy and immunotherapy combined with radiotherapy (CIR) from October 9, 2018 to June 1, 2022. Irradiation was only delivered to the primary tumor and retropharyngeal nodes (GTVnx+rn) and gross cervical lymph nodes (GTVnd). Results The median follow‐up was 45 (range, 15–67) months. There was no recurrence in the omitted elective regions. The 36‐month LRRFS, PFS, and OS were 95.4%, 44.6%, and 90.8%, respectively. The main grade 3/4 hematologic toxicities were neutropenia (42.2%), anemia (20.0%), and thrombocytopenia (13.3%). The incidence of acute grade 3/4 dermatitis, mucositis, and xerostomia were 4.4%, 8.9%, and 4.4%, respectively. Conclusions Omitting CTV1 and CTV2 was well‐tolerated and provided favorable clinical outcomes in the era of immunotherapy.