ESTRO 2020 Abstract book

S43 ESTRO 2020

Patient cohorts were well-balanced in key socioeconomic (race, sex, insurance, income & education) & clinical characteristics (tumor site, grade, size & surgical margin status). Patients in the CRT arm were more likely to be younger (≤50) (44.9% vs 20.8%), have a Charlson-Deyo [CD] score of 0 (85.7% vs 79.3%) & have synovial sarcoma histology (19.6% vs 2.8%). The unadjusted 5-year KM OS was significantly higher in the CRT vs RT cohort: 72.0% vs 56.1% on univariate (p<0.0001) & multivariate analysis (Hazard Ratio [HR]: 0.57; 95% Confidence Interval [CI]: 0.41-0.78; p<0.001) even after adjusting for age, race, income, CD score, histology, tumor size, tumor grade & primary site (lower extremity; upper extremity; trunk). PSM identified evenly matched cohorts of 212 patients each with respect to age, income, CD score, histology, grade, tumor size & primary site. The adjusted 5-year KM OS was significantly higher in the CRT vs RT cohort: 69.8% vs 55.4%. The addition of neoadjuvant C remained prognostic for OS on PSM analysis (HR: 0.56 [0.39-0.83], p=0.003). There were no statistical differences in the mean surgical inpatient stay (3.8 vs 4.3 days), 30-day unplanned readmission rate (5.0% each), or 90-day mortality (2.0% vs 1.2%) between the RT vs CRT cohorts. Conclusion The addition of chemotherapy to neoadjuvant RT was associated with improved OS in patients with high risk ET- STS in the NCDB. Additionally, toxicity surrogates were similar between RT vs CRT cohorts. These findings warrant further investigation in a prospective randomized trial. OC-0089 Oncological & Functional outcomes of Extracorporeal Radiation and Reimplantation for Bone Sarcomas K. Jani 1 , M. Shah 2 , S. Batham 1 , M. Jain 1 , M. Gandhi 1 , P. Hirpara 3 1 HCG Cancer Centre, Department of Radiation Oncology, Ahmedabad, India ; 2 Sparsh Hospital, Department of Ortho Oncology, Ahmedabad, India ; 3 HCG Hospital, Department of Radiation Oncology, Bhavnagar, India Purpose or Objective We analysed oncological and functional outcomes of Extracorporeal radiotherapy (ECRT) and reimplantation done for bone sarcomas. Material and Methods 27 patients (14 osteosarcoma, 10 Ewing’s sarcoma, 3 others; mean age 13 years) were treated with ECRT between 2010 and 2016. Femur was commonest bone (18) followed by tibia (6) and humerus (3). 26 had a metadiaphyseal while 2 had osteoarticular resections. A single dose of 50 Gy was delivered to the resected bone segments. The irradiated bones were reimplanted immediately as a biological graft. Construct was stabilized with long locking plates. Osteoarticular ECRT was coupled with joint replacement. Patients were treated with chemotherapy as per standard protocol. Results All 27 patients were available at a mean follow-up of 34 months (24 to 74). The mean time to union for all osteotomy sites was 6 months (2 to 17): metaphyseal osteotomy sites united quicker than diaphyseal osteotomy sites. 3 nonunions needed bone grafting. 1 deep infection necessitated removal of the ECRT segment. There was 1 local recurrence in soft-tissue. At the time of final follow- up, 19 patients were free of disease, one was alive with disease and 7 had died of disease. The mean Musculoskeletal Tumor Society Score at the last follow-up was 26 (18 to 30). Conclusion The radiated bone acts as a size matches allograft and has very good union rates. The complication rates are very low. Extracorporeal irradiation is an oncologically safe and biological reconstruction technique for limb salvage in

Individualized dose constraints were used for bone and skin corridor. An intraoperative radiation therapy (IORT) boost was planned for expected close or positive surgical margins. Results Between August 2006 and January 2019, 147 pts ( M/F:89 /58), median age: 65 yrs (20-89) with extremity (122pts) and superficial trunk (25pts) underwent to RT with 40.5Gy/18frs. Pts with primary disease were 111(75,5%) and 36 pts (24,5%) had recurrent disease. Most common histologic types were LipoSa (35,3%), PleomorphicSa (17%), LeiomyoSa 17(11%) and MixofibroSa (8%). Overall, 50 pts (34%) had G1, 41( 28%) G2 and 56 pts (38%) had G3 disease. All but 3 pts completed the planned 40.5 Gy. At surgery, 115 pts (78%) had R0 resection and 32 pts (22%) R1 resesction; 94 pts ( 64%) underwent IORT for close or positive margins at surgery. Only 5 pts (3,4%) had G3 acute skin toxicity. Major postoperative complications ( SR2 criteria) were reported in 19/147 pts (13%). At a median follow up of 33 months ( range 9-108 ) the DFS and OS at 2 and 5 years were 82% and 68%, and 87,4% and 71,4% , respectively. The cumulative incidence of local recurrence (LR) and distant metastases at 5 years were 13% and 26% respectively. No significant difference in LR were reported in IORT and no-IORT pt subgroup ( Long Rank p=0,4) Conclusion Preoperative moderate Hypofractionation RT with 40.5Gy/18 frs, 2.25 Gy/ fr for Extremity and superficial trunk STS appears safe and feasible with favourable oncologic outcomes. Dose escalation with IORT is feasible, when need. This results provide an available evidence, well comparable with standard dose and fractionation, and could be useful for further investigations OC-0088 Neoadjuvant Radiotherapy vs Chemoradiotherapy for High-Risk Extremity and Trunk Soft Tissue Sarcoma M. Chowdhary 1 , A. Chowdhary 2 , N. Sen 1 , N. Zaorsky 3 , K. Patel 4 , D. Wang 1 1 Rush University Medical Center, Radiation Oncology, Chicago, USA ; 2 Robert H. Lurie Comprehensive Cancer Center- Northwestern University, Hematology and Medical Oncology, Chicago, USA ; 3 Penn State Cancer Institute, Radiation Oncology, Hershey, USA ; 4 Yale School of Medicine, Therapeutic Radiology, New Havent, USA Purpose or Objective Patients with large, high-grade extremity and trunk (ET) soft-tissue sarcomas (STS) are at high risk for distant recurrence and death. The integration of chemotherapy (C) to standard of care neoadjuvant radiotherapy (RT) remains controversial even for these patients due to conflicting trial results and toxicity concerns. This study examines the impact of adding C to neoadjuvant RT on overall survival (OS) in high risk ET-STS. Material and Methods The National Cancer Data Base (NCDB) was queried for patients ≥18 years with high risk (≥5 cm + FNCLCC grade 2- 3) ET-STS (histology per NRG DT001) who received neoadjuvant RT and limb sparing surgery from 2006-2014. Patients were stratified based upon receipt of C (RT and CRT cohorts). Overall survival (OS) for RT vs CRT cohorts was analyzed using the Kaplan-Meier (KM) method, log-rank test & Cox proportional hazards models. Propensity score-matched analysis (PSM) was employed to account for potential treatment selection bias between cohorts. Mean inpatient stay, 30-day unplanned readmission rate and 90-day mortality were calculated as surrogates for toxicity. Results A total of 884 patients were identified: 639 (72.3%) in the RT cohort & 245 (27.7%) in the CRT cohort.

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