Sarcoma and Cutaneous Tumors

PV QA 2 - Poster Viewing Q&A 2

MO_22_2510 - Role of radiation therapy in high-grade, small soft tissue sarcomas

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Role of radiation therapy in high-grade, small soft tissue sarcomas
N. B. Figura1, G. Q. Yang2, K. A. Ahmed3, and A. O. Naghavi3; 1Moffitt Cancer Center, Tampa, FL, 2H. Lee Moffitt Cancer Center and Research Institute, Department of Radiation Oncology, Tampa, FL, 3H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL

Purpose/Objective(s): In soft tissue sarcoma (STS), surgery is the primary component of treatment. Risk of local recurrence is lower when resected with clear margins, patient age ≤50, and with the addition of radiotherapy (RT). In small (<5cm) high grade STS, resected with clear margins, there is controversy whether RT offers a significant benefit to surgery alone. We hypothesized that the addition of RT to small high-grade STS may improve outcome in a large population-based cohort.

Materials/Methods: The National Cancer Data Base (NCDB) was queried for patients diagnosed with clinically T1N0M0, high grade STS from 2004 to 2015. All patients had negative surgical margins at the time of resection, with a minimum of 3 months follow up. Patients diagnosed with pathologic nodal involvement or received chemotherapy were excluded from the analysis. Patient characteristics were compared via Pearson-chi square test and Mann-Whitney U-test as appropriate. Overall survival (OS) was estimated by Kaplan-Meier with predictors assessed via log-rank for univariate analysis, and Cox regression multivariate analysis (MVA).

Results: A total of 2895 STS patients were identified, with a median follow-up of 47 months (3-148 months). Patients were treated with surgery, either with (n=1349, 47%) or without (n= 1546, 53%) RT. The most common histologies encountered were giant cell sarcoma (17%), leiomyosarcoma (17%), pleomorphic sarcoma (15%), and nonspecified sarcoma (8%). The median age of patients was 65 (18-90) with tumor size of 35mm (interquartile range 25-45mm). Patients were primarily Charlson-Deyo comorbidity score (CDCS) ≤1 (n=2779, 96%), within the highest income quartile (n=1018, 35%), and >50 years of age (n=2228, 77%). There was no difference in age (>50 vs ≤ 50 years), gender, CDCS, or income level between the RT and no RT groups (p>0.05 for all). Patients receiving RT were more likely to have larger tumors (median 38mm vs 34 mm, p<0.01), when compared to the surgery alone group. The addition of RT was associated with nearly an 18 month absolute increase in median survival (125 vs 143 months), translating to an improvement in 5-year OS (78% vs 72%, p<0.01). RT’s OS benefit persisted on MVA (HR 0.82, 95%CI 0.71-0.95, p=0.01). Other variables associated with OS on MVA include worse CDCS (HR 1.2, 95%CI 1.1-1.4, p<0.01) and increasing age (HR 1.04 95% CI 1.03-1.05 p<0.01). On subset analysis stratified by age, age >50 (median 70, 51-90) had a more pronounced RT benefit on MVA (HR 0.81, 95% CI 0.69-0.95, p=0.01), whereas age ≤ 50 (median 40, 18-50) found no OS benefit with the addition of RT (HR 0.96 95% CI 0.61-1.51, p=0.85).

Conclusion: In this large population based analysis, patients with a small high grade STS resected with clear margins, the addition of RT independently predicted for an improvement in OS. This benefit was most pronounced in patients >50 years of age, identifying a higher risk cohort where the addition of RT should be strongly considered.

Author Disclosure: N.B. Figura: None. G.Q. Yang: None. K.A. Ahmed: None. A.O. Naghavi: None.

Nicholas Figura, MD

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