Abstract 5244: Radiation-associated sarcoma exhibits worse outcomes than sporadic sarcoma
Authors: Raynor Abigail , Oh Amy , Chang Wen-I , Honeyman Joshua 
Published: June 2022

Background: Radiation-associated sarcoma (RAS) occurs following ionizing radiation exposure from a therapeutic or environmental source. Because half of all cancer patients will receive radiation therapy (RT), there is a need to understand the etiology of radiation-induced sarcomas, as these cancers are thought to exhibit worse outcomes than their sporadic counterparts.

Methods: A retrospective single-center analysis of sarcoma patients treated from 2013-2019 was conducted. Univariate and survival analyses were used to distinguish the characteristics of RAS and sporadic sarcoma (SS), and further assess differences in disease presentation, cancer treatment, and survival between the two groups.

Results: The incidence of RAS during the study period was 6%. Breast (25%), prostate (25%) and colorectal (15%) cancers were the most common primary tumors associated with RAS development. There was substantial variation in the characteristics of the two groups, with noted differences in the histologic compositions, clinical stage at presentation, and overall survival (Table 1). The most frequent RAS histologies were angiosarcoma (30%), leiomyosarcoma (25%) and undifferentiated pleomorphic sarcoma (20%), while the most frequent SS subtypes were liposarcoma (15.5%), carcinosarcoma (13.5%) and leiomyosarcoma (11.9%). No patients with RAS had a known genetic cancer predisposition. A higher percentage of RAS patients presented at later clinical stages, as 75% of all RAS cases versus 41.9% of all SS cases were diagnosed at stage III/IV (p=0.004). RAS also exhibited overall worse outcomes, as the 5-year survival was significantly decreased compared to SS (32.6 vs 60.3%, p=0.027).

Conclusion: Our study identifies marked differences in the disease characteristics and clinical outcomes of RAS and SS. Further research into cancer predisposition, biomarkers of risk, and molecular pathways of disease is essential to provide individualized care to patients with RAS.

Table 1. Summary of Sporadic Sarcoma and Radiation-Associated Sarcoma Characteristics Sporadic Sarcoma Radiation-Associated Sarcoma P-Value Count 310 20 Median Age at Diagnosis (Years) 58.51 (0.02-87.74) 68.81 (48.09-84.19) 0.003 Location Trunk 109 (35.2%) Trunk 10 (50.0%) Lower Extremity 97 (31.3%) Lower Extremity 2 (10.0%) Head/Neck 36 ( 11.6%) Retroperitoneal 4 (20.0%) Other 68 (21.9%) Other 4 (20.0%) Histologic Subtype Liposarcoma 48 (15.5%) Angiosarcoma 6 (30.0%) Carcinosarcoma 42 (13.5%) Leiomyosarcoma 5 (25.0%) Leiomyosarcoma 37 (11.9%) UPS 4 (20.0%) Chondrosarcoma 36 (11.6%) Liposarcoma 3 (15.0%) Other 147 (47.4%) Other 2 (10%) Clinical Stage I & II 146 (47.1%) 4 (20.0%) 0.01 III & IV 130 (41.9%) 15 (75.0%) 0.004 Unknown 34 (11.0%) 1 (5.0%) Treatments Surgery 244 (78.7%) 12 (60.0%) 0.12 Radiation 91 (29.4%) 10 (50.0%) 0.95 Chemotherapy 105 (33.6%) 7 (35.0%) 0.35 Status at Follow-Up NED 139 (44.8% ) 6 (30.0%) AWD 74 (23.9%) 3 (15.0%) Deceased 97 (31.3%) 11 (55.0%) Five-Year Survival 60.3% 32.6% 0.027

Citation Format: Abigail Raynor, Amy Oh, Wen-I Chang, Joshua Honeyman. Radiation-associated sarcoma exhibits worse outcomes than sporadic sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5244.