Sarcoma and Cutaneous Tumors

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MO_22_2755 - Preoperative Hypofractionated Radiation Therapy in Soft Tissue Sarcoma of the Extremity: Outcomes from the National Cancer Database.

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

Preoperative Hypofractionated Radiation Therapy in Soft Tissue Sarcoma of the Extremity: Outcomes from the National Cancer Database.
S. Scheick1, B. J. Ager1, M. M. Poppe2, and Y. J. Hitchcock1; 1University of Utah Huntsman Cancer Institute, Salt Lake City, UT, 2Huntsman Cancer Institute, Salt Lake City, UT

Purpose/Objective(s): Hypofractionated radiotherapy for soft tissue sarcoma (STS) of the extremity is an attractive alternative to standard radiation courses due to decreased overall treatment time, cost of care, improved patient convenience, and possibly improved tumor cell kill. We aimed to investigate the patterns of care and overall survival (OS) of patients with STS of the extremity receiving preoperative radiation with either a standard or hypofractionated course of radiotherapy.

Materials/Methods: Adult patients with a STS of the extremity who underwent pre-operative radiotherapy and definitive surgical resection from 2004 to 2013 were included from the National Cancer Database (NCDB). Patients were excluded if they received a dose per fraction <1.8Gy or >6.0Gy or if they received a total dose <25.0Gy or greater than >50.4Gy. Standard fractionation (SRT) was defined as 1.8-2.0Gy/fraction. Hypofractionated radiotherapy (HRT) was defined as >2.0Gy/fraction. Logistic and Cox regression modeling was used to identify factors predictive of receipt of HRT, unplanned readmission after surgery, positive margins, and OS. Survival analysis was performed with Kaplan Meier and log rank analysis.

Results: 2,359 patients were included. 2,171 patients (92%) received SRT. 188 patients (7%) received HRT. The median total dose in the SRT group was 50.0Gy and the median dose per fraction was 2.0Gy. The median total dose in the HRT group was 28.0Gy and the median dose per fraction was 3.0Gy. Predictors of receiving HRT on multivariate analysis included size >10cm (OR 2.52, 95% CI 1.38 to 4.58) and spindle cell histology (OR 2.11, 95% CI 1.01 to 4.4). The only negative predictor of receiving HRT included liposarcoma histology (OR 0.43, 95% CI 0.22 to 0.82). Of those with an unplanned readmission after surgery, 72 patients (86%) received SRT and 12 (14%) received HRT. The only positive predictor of unplanned readmission was size >10cm (OR 4.70, 95% CI 1.42 to 15.53). HRT was not associated with unplanned readmission (OR 1.8, 95 CI 0.88 to 3.73). Of those with positive margins after surgery, 163 patients (7.5%) were treated with SRT and 14 patients (7.4%) with HRT . Positive predictors of positive margins included age >65 (OR 1.62, 95 CI% 1.13 to 2.31) and histology including fibromatous sarcoma (OR 2.08, 95% CI 1.10 to 3.93) and myxosarcoma (OR 3.34, 95% CI 1.23 to 9.10). HRT was not associated with positive margins (OR 1.00, 95% CI 0.52 to 1.92). No survival benefit with HRT was noted on univariate or multivariate analysis. Worse OS was associated with age >65 (HR 2.04, 95% CI 1.45 to 2.87), size >10cm (HR 2.24, 95% CI 1.65 to 3.04), poorly differentiated tumors (HR 2.04, 95% CI 1.34 to 3.14), and hemangiosarcoma (HR 2.94, 95% CI 1.07 to 8.07).

Conclusion: Preoperative hypofractionated radiotherapy does not appear to have increased toxicity or inferior OS when compared to conventional fractionation.

Author Disclosure: S. Scheick: None. B.J. Ager: None. M.M. Poppe: Member; Accreditation Council for Graduate Medical Educati. Y.J. Hitchcock: None.

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