Long‐Term Clinical Outcome and Quality of Life of Children, Adolescents, and Young Adults With Chordoma or Chondrosarcoma Treated With Pencil Beam Scanning Proton Therapy

ABSTRACT Background and Aims To assess clinical outcomes and quality of life (QoL) of children, adolescents, and young adults (C‐AYAs) with chordomas (CH) or chondrosarcomas (CS) after pencil beam scanning proton therapy (pbsPT). Methods A total of 76 C‐AYAs treated between 1999 and 2023 were included. Median age was 16.6 years (1.5–25.4). A total of 44 (57.9%) were AYAs (15–25 years). Most tumors were CHs ( n = 49; 64.5%) and located in the skull base (68.4%). Median radiation dose was 73.8 Gy (RBE) (54–75.6). A total of 26 (34.2%) patients underwent complete resection. PEDQOL questionnaire was used to assess QoL. Kaplan–Meier and log‐rank tests were used for the analysis. Results With a median follow‐up of 88.4 months (range, 1.8–257.6), 9 (11.8%) patients died. Local failure only developed in 9 (11.8%) patients. Two (2.6%) presented with distant failure only and another (1.3%) had both. Seven‐years overall survival (OS), local control (LC), and distant control (DC) were 86.3%, 87.7%, and 95.7%, respectively. Children when compared to AYAs had worse 7‐years DC (90% vs. 100%, p = 0.049). Surgical resection vs. biopsy was associated with better 7‐years LC (87.1% vs. 67.7%, p = 0.031). Recurrent tumors showed worse OS, LC, and DC (94.5% vs. 44.6%, p < 0.001; 93.2% vs. 36.6%, p < 0.001; 98.3% vs. 77.6%, p = 0.003). Seven‐years freedom from grade ≥3 late toxicity was 83.1%. Three (3.9%) children with CH developed secondary tumors. QoL did not differ from a healthy cohort 2 years after pbsPT. Conclusions Excellent clinical outcomes with acceptable long‐term toxicity and QoL were observed for C‐AYAs with CH/CS after pbsPT. Recurrent tumors, young age, and lack of surgical resection were associated with worse prognosis.