2132 - Tailoring Adjuvant Radiotherapy for Ewings Sarcoma: Lessons Learnt
Presenter(s)
S. Laskar1, S. A. Uppor1, J. Manjali1, N. R. Khanna1, A. Puri1, A. Gulia2, P. Nayak3, M. Pruthi1, S. Qureshi1, G. Chinnaswamy4, M. Prasad4, B. Parambil5, P. Bhargava1, S. Rath6, A. Janu3, A. Baheti7, V. Patil5, N. Purandare3, S. Shah6, B. Rekhi3, M. Ramadwar8, C. Pramesh1, D. Nair1, and G. Pantavaidya1; 1Tata Memorial Centre, Homi Bhabha National Institute, Mumbai, India, 2Homi Bhabha Cancer Hospital, New Chandigarh, India, 3Tata Memorial Centre, Mumbai, India, 4Department of Pediatric Oncology, Tata Memorial Centre, Homi Bhabha National Institute, Mumbai, India, 5Tata Memorial Hospital, Mumbai, India, 6Tata Memorial Hospital, Tata Memorial Centre, Homi Bhabha National Institute, Mumbai, India, 7Department of Radiodiagnosis, Tata Memorial Centre, Homi Bhabha National Institute, Mumbai, India, 8HBNI University, MUMBAI, India
Purpose/Objective(s):
To evaluate the prognostic factors influencing outcomes in patients with Ewing’s sarcoma (ES) treated with chemotherapy (CTh), Surgery (Sx) and Postoperative adjuvant Radiotherapy (PORT).Materials/Methods:
From January 2010 to July 2022, patients receiving PORT as part of a multimodality approach in the management of ES were retrospectively analyzed.Results:
A total of 345 patients with a median age of 15 years (range 1-53 yrs) were included (53% were between 10-20 yrs). Males comprised 64.9%. The commonest presenting symptom was pain and swelling (51.1%). Majority (82%) of the tumors were skeletal in origin. The commonest site was long bones (48%), chest wall (17%), Head & Neck (15%), & Pelvis (10%). Femur was the commonest bone involved (37.8%), followed by humerus (25.2%). At presentation, 10% had metastatic disease. Majority (82.8 %) received Induction CTh followed by Sx and PORT. Percentage necrosis in the resected specimen was 100% in 26.2%, 90-99% in 22.7%, & <90% in 51% patients. The resection margin status were R0 in 94.4%, R1 in 3.5%, and R2 in 2% patients. Most (97%) received external beam radiotherapy (EBRT) and 3% were treated with brachytherapy. After a median follow-up of 40 months (IQR: 23-68 months) the Local control (LC), progression free survival (PFS) and overall survival (OS) at 5 years were 91.6%, 64.5% and 87.6% respectively. Skeletal tumors had superior LC compared to extra-skeletal disease (94.3% vs 79.9%; p=0.015). Patients with tumor necrosis = 90 had better LC compared to <90% necrosis (96.1% vs 84.8%; p=0.010). These factors retained significance for LC on multivariate analysis. Patients with R0 resection had better LC (91.5% vs 90%; p-value: 0.680). In terms of PFS, patients aged <15 yrs fared better (72.4% vs 57.6%; p = 0.012). Patients with necrosis =90% had better PFS than <90% (74.9% vs 51.5%; p= <0.010). Extremity long bones had better PFS (85.2%) followed by pelvic disease (64.3%). Visceral involvement resulted in poor PFS (34.6%) (p=0.005). Percentage necrosis remained significant for PFS on multivariate analysis. High lactate dehydrogenase (LDH) levels at diagnosis (= 200 U/L) were associated with poorer OS (82.2% vs 97.7%; p-value: 0.030). Patients with Lung metastasis at diagnosis had a better OS compared to patients with bone metastasis (90% vs 50%; p=0.410). Grade 2 late toxicities were documented in 3.2%. Non-biolopgical prosthesis was used in 15.8% of whom 1 patient developed loosening of prosthesis 2 years post RT. No cases of second malignancy were noted.Conclusion:
Tumor location, percentage necrosis & surgical margins impact LC, PFS & OS. Our results highlights the significance of tailoring PORT based on the histological response, surgical margins, and pretreatment tumor characteristics.