2337 - Outcomes Following Combined Modality Local Therapy vs. Surgery Alone for Patients with Non-Metastatic Intrathoracic Soft Tissue Sarcomas
Presenter(s)
T. S. Kanala1, Z. Hooda2, A. K. Yoder1, D. Mitra1, A. J. Bishop1, D. Araujo3, R. Ratan3, N. Somaiah3, E. F. Nassif Haddad3, R. Rajaram2, A. A. Vaporciyan2, D. C. Rice2, B. A. Guadagnolo1, K. G. Mitchell2, and A. Farooqi1; 1Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 2Department of Thoracic and Cardiovascular Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX, 3Department of Sarcoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
Purpose/Objective(s): Intrathoracic soft tissue sarcomas (STS) are rare malignancies. Given the difficulty of achieving a wide negative margin, radiation therapy (RT) is often considered along with surgery (Sx), extrapolating based on benefits observed for STS in other anatomic sites. We sought to investigate the role of combined modality therapy (CMT) among patients with localized intrathoracic STS.
Materials/Methods: We performed a single-institution retrospective study of non-metastatic localized STS treated with curative intent therapy between 1980 and 2023. STS arising in the chest wall were excluded. The Kaplan-Meier method was used to estimate disease-specific survival (DSS), distant metastasis-free survival (DMFS), and local recurrence-free survival (LRFS). Univariate analyses (UVA) were performed using the Log rank test. Multivariable analysis (MVA) for DSS was performed using Cox proportional hazards.
Results:
Among 62 patients, 31(50%) underwent CMT and 31(50%) underwent surgery alone as local therapy. In the CMT group, 22 (71%) patients received adjuvant RT to a median dose of 60Gy whereas 9 (29%) received RT preoperatively to a median dose of 50Gy. Synovial sarcoma (n=16, 26%) was the most common histology. Patients receiving CMT had higher risk tumor characteristics for local recurrence including predominantly mediastinal primaries (68% vs 19%, p<0.001), a higher proportion of T3-T4 tumors (68% vs 39%, p=0.02), and positive/uncertain surgical margins (48% vs 19%, p=0.02). The number of patients receiving either neoadjuvant or adjuvant systemic therapy did not differ significantly between the two groups (75% Vs 54%, p=0.1). The median follow-up was 29 months. Three-year LRFS, DMFS, and DSS in the entire cohort were 51% (95% CI 38 – 70), 65% (95% CI 52 – 80) and 77% (95% CI 66 – 90). The median times to local recurrence (n=24) and distant metastases (n=22) were 11.5 months (95% CI 9 – 30) and 13 months (95% CI 7 – 25). Three-year LRFS, DMFS, and DSS were not significantly different between CMT (50%, 61% & 70%) and Sx (53%, 75% and 87%) groups. On UVA, factors such as tumor size, histological grade, and treatment era (before or in/after 2005) were not found to be significantly associated with outcomes. A wide negative margin resection numerically had a better LRFS but did not achieve statistical significance (59% Vs 36%, p=0.07), and local recurrence was strongly associated with inferior DSS (65% vs 88%, p<0.005). On MVA, no independent predictors of DSS were identified, including T stage, margin status, or tumor location. Three patients (10%) in the CMT group experienced >/= Grade 3 late toxicity.Conclusion: Among this cohort of localized intrathoracic STS, CMT was preferentially utilized in patients with baseline higher-risk features including higher T-stage, mediastinal location, and margin+ resections. Despite this, CMT yielded comparable LRFS, DMFS, and DSS to the Sx group, suggesting that RT may help offset the higher baseline risk of local failure in complex intrathoracic sarcomas.