2151 - Proton Beam Therapy Improves Survival in Sarcoma Patients: Evidence from NCDB Analysis

Purpose/Objective(s): The objective of this study is to explore the factors associated with the use of PBT and its impact on the overall survival (OS) of sarcoma patients.

Materials/Methods: The data for the study were extracted from the National Cancer Database. Multivariable logistic regression analysis was performed to identify the factors associated with the use of PBT. The OS of the patients was assessed by multivariable Cox regression analysis. The multivariable analyses were adjusted for age at diagnosis, sex, race, education, income, insurance status, histology, comorbidity score, radiation therapy dose, chemotherapy, surgery, and year of diagnosis.

Results: Of the 117,694 sarcoma patients, 3,573 (3%) received PBT. The use of PBT increased from 1.4% in 2004 to 12% in 2022. Young age, non-white non-black, and 60-80 Gy dose were positively associated with the use of PBT. Patients with Medicaid, Medicare, other governmental insurance or without health insurance (compared to private insurance), with rhabdomyosarcoma, Ewing sarcoma, chondrosarcoma, osteosarcoma, and other histologic types (compared to chordoma), living an area with income <=$50,353, having a comorbidity score of 1 or>=2 (compared to 0), being diagnosed between 2004-2013, and not receiving chemotherapy were all less likely to receive PBT (vs. ph_RT).

Patients who received PBT had longer OS compared to those who received Ph_RT (HR: 0.73). In subset analysis stratified by histology, PBT (vs. Ph_RT) was associated with improved OS among patients diagnosed with chordoma (HR: 0.57), rhabdomyosarcoma (HR: 0.58) and chondrosarcoma (HR: 0.35) but not in those with Ewing sarcoma or osteosarcoma. When stratified by surgical status, patients with definitive surgery who received PBT (vs. Ph_RT) was associated with improved OS in chordoma (HR: 0.37), chondrosarcoma (HR: 0.52) and osteosarcoma (HR: 0.32) but not rhabdomyosarcoma and Ewing sarcoma. Among patients who did not undergo surgery, PBT (vs. Ph_RT) was associated with improved OS in chordoma (HR: 0.57), rhabdomyosarcoma (HR:0.56), chondrosarcoma (HR:0.24), osteosarcoma (HR: 0.51) and other histologic types (HR:0.76) but not Ewing sarcoma. When the analysis was limited to RT dose of 60-80 Gy and stratified by surgery, improved OS with PBT (vs. Ph_RT) was observed only in patients with definitive surgery diagnosed with chordoma (HR: 0.36) but not in those with chondrosarcoma, whereas among non-surgical patients, PBT (vs. Ph_RT) was associated with improved OS in both chordoma (HR: 0.56) and chondrosarcoma (HR: 0.26). All of these findings were statistically significant (p < 0.05).

Conclusion: The use of PBT was associated with improved OS compared to photon RT in sarcoma patients. In the stratified analysis by histology, the use of PBT was associated with improved OS in patients diagnosed with chordoma, rhabdomyosarcoma, or chondrosarcoma. Although the use of PBT among sarcoma patients has increased, more work is needed to achieve broader adoption.