Positive margins (PM) remain after surgery in some soft-tissue sarcoma (STS) patients. We investigated the efficacy of radiation therapy (RT) in STS patients with PM.

A retrospective chart review was performed on 154 patients with STS at various anatomic sites with PM, defined as tumor on ink, who underwent RT with curative intent between 1970 and 2001. Local control (LC), disease-free survival (DFS), and overall survival (OS) rates were evaluated by univariate (log-rank) and multivariate analysis of prognostic and treatment factors.

At 5 years, actuarial LC, DFS, and OS rates were: 76%, 46.7%, and 65.2%, respectively. LC was highest with extremity lesions (p < 0.01), radiation dose >64 Gy (p < 0.05), microscopically (vs. grossly visible) positive margin (p = 0.03), and superficial lesions (p = 0.05). Patients receiving >64 Gy had higher 5-year LC, DFS, and OS rates of 85%, 52.1%, and 67.8% vs. 66.1%, 41.8%, and 62.9% if < or =64 Gy, p < 0.04. OS was worse in patients with G2/G3 tumors with local failure (LF), 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. < or =64 Gy), p < 0.05; the best predictors for OS were size, p < 0.001, gross vs. microscopic PM, p < 0.05, and LF, p < 0.01.

Local control is achieved in most PM STS patients undergoing RT. Doses >64 Gy, superficial location, and extremity site are associated with improved LC. OS is worse in patients with tumors with lesions >5 cm, grossly positive margins, and after local failure.