Radiation Therapy for Control of Soft Tissue Sarcomas Resected with Positive Margins

Abstract

Purpose/Objective: Surgery and radiation therapy (XRT) are employed for treatment of most patients with soft tissue sarcoma (STS). Surgical sparing of normal structures results in positive margins (PM) in some STS patients. Prior studies have documented the adverse impact of a PM in these patients. We have investigated the efficacy of treatment in patients with a positive margin (PM) and evaluated the impact of patient and treatment characteristics on outcome. Materials/Methods: Retrospective chart review was performed on 154 STS patients with PM who were identified in our departmental sarcoma database and who underwent XRT between 1970 and 2001. Tumor location: lower (48%) and upper (20%) extremity, head/neck 15%, retroperitoneal 11%, and trunk 6%. Grade: G1 8%, G2 51%, G3 41%. Local control (LC), disease-free survival (DFS) and overall survival (OS) rates were evaluated by univariate (log-rank) and multivariate analysis with regard to known STS prognostic factors. Results: Median follow-up for living patients is 101 (range: 29–371) months. Surgical procedures were intralesional (32%), marginal (27%), excisional biopsy (22%), and wide excision (19%) Median tumor size was 6 cm (range 1.5–33 cm). Depth was 88% deep and 12% superficial. Median XRT dose was 64 Gy (range: 20–77 Gy). Chemotherapy was given to 15% of patients. At 2 and 5 years, actuarial LC, DFS, and OS rates were: 84.9% and 76%, 65.6% and 46.7 %, and 81.1% and 65.2% respectively. Patients with grossly PM tended to fare worse, with LC and OS at 5 years of 67% and 52.2% versus 81% and 73.4% with microscopic PM, p=0.09. LC was better in superficial lesions, 93.3% vs. 66%, p=0.05. LC was highest in patients with extremity lesions. Patients receiving >64 Gy had 5-year LC, DFS and OS rates of 85%, 52.1% and 67.8% versus 66.1%, 41.8% and 62.9% if <≤ 64 Gy, p<0.04. LC was significantly higher in patients receiving doses >64 Gy (see figure). OS in patients with G2/G3 tumors at 5 years was 67.3% in patients with LC versus 49.2% if local failure (LF) occurred, p< 0.001. Other known prognostic factors including grade, stage, size, and age (>≥ 50) also significantly influenced OS. By multivariate analysis, the best predictors of LC were site (extremity vs. other) p<0.01 and dose (> 64 vs. ≤ 64 Gy) p<0.05; the best predictor of DM was size (≤ 5 cm vs. > 5 cm), p<0.05; and the best predictors for OS were size p<0.001, gross versus microscopic PM p<0.05, and LF p<0.01. Conclusions: Radiation therapy secures LC in most STS patients resected with positive margins. Doses > 64 Gy, superficial location, and extremity site are associated with improved local control. Overall survival is worse in patients with lesions > 5 cm, grossly PM, and LF.