Hypofractionated Preoperative Radiotherapy 30Gy in Five Fractions for Soft Tissue Sarcoma of the Extremity

Abstract

Hypofractionated preoperative radiotherapy (HypoRT) is being used with increasing frequency for soft tissue sarcomas (STS) of the extremities. Besides the social and economic advantages, HypoRT has a theoretical advantage in STS because of their low α/β ratio. The objective of this study is to review our experience using HypoRT to a dose of 30Gy in 5 fractions in STS of the extremities. This study is a retrospective review of patients with extremity STS treated at our center with preoperative HypoRT to a dose of 30Gy in 5 fractions given on alternate days over 2 weeks. Inclusion criteria were age ≥18 years, biopsy-proven primary STS in an extremity, and fitness for surgery. The primary endpoint was major wound complications (MWC) defined as the need for wound management or secondary operation under general or regional anesthesia within 120 days from surgery. Secondary objectives were: early toxicity grade ≥ 2 and clinical outcomes, including local control (LC), and metastasis-free survival (MFS). Descriptive statistics were used to evaluate patient and treatment characteristics. The Kaplan-Meier method was used to estimate survival. A total of 40 patients received preoperative HypoRT at our center between 2016 and 2022. The median age was 70 years (30 - 91). Males accounted for 57.5% of the patients. The most common primary site was the lower extremity (62.5%). The most prevalent histologic type was myxofibrosarcoma (27.5%), followed by pleomorphic spindle cell sarcoma (20%). All patients were treated with image-guided intensity modulated radiotherapy with margins for the CTV as tested in the RTOG 0630 study. Median follow-up was 14.8 months (5 - 86). Acute side effects were seen in 80% of the patients, all grade <3. The most common toxicity was dermatitis (37.5%), the second was fatigue (20%), and the third was pain (15%). Surgery was performed in all cases after a median interval from completion of HypoRT of 34 days (16-59). Amputation was performed in one patient with a fungating tumor, HypoRT having been aborted at only 24Gy because of worsening symptoms. On pathologic examination, positive margins were found in four cases (10%). The percentage of necrosis was ≥ 90% in 7 patients and 50%-90% in 10. MWC occurred in 13 patients (32.5%), including 10 who underwent a procedure with anesthesia. Sixteen patients were treated for a wound infection. Only one patient recurred locally. Two-year LC was 91.7%. MFS was 87.4% at 6 months and 60.8% at 2 years. DFS was 84.9% at 6 months and 64.8% at 2 years. The preoperative HypoRT regimen of 30Gy in 5 fractions given on alternate days for extremity STS is safe. Acute toxicity was not different from our previous experience using the conventional regimen of 50Gy in 25 fractions over 5 weeks and the MWC rate was comparable to that reported for the conventional regimen. Local control was excellent.