Low-grade soft-tissue sarcomas: What is an adequate margin for local disease control?

Background: Whilst the resection margin is an established factor predictive of local control of soft-tissue sarcomas (STSs), the adequacy of margin width for low-grade STSs has been rarely described. We aimed to investigate the margin adequacy and its prognostic relevance in low-grade STSs. Methods: 109 patients who underwent surgical treatment for a low-grade STS were studied. The prognostic value of margin status was evaluated according to the R–, R+1–classification, and width in millimetres. Results: The 10-year local recurrence (LR) rates were 6%, 27%, 54% in R0, R1, and R2, respectively (p < 0.001), according to the R–classification. The R+1–classification resulted in a decreased LR rate in R1, but no major differences in LR rates in R0 and R2; 7%, 14%, 54% in R0, R1, and R2, respectively (p < 0.001). When classified by metric distance, 10-year LR rates were 0%, 8%, and 38% by ≥ 2.0 mm, 0.1–1.9 mm, and 0 mm margins, respectively (p < 0.001). Patients with close margins (0.1–1.9 mm) who received adjuvant radiotherapy had a trend toward lower LR risk than those without radiotherapy (10-year, 4% vs. 12%; p = 0.406). The 5 and 10-year disease-specific mortality was 9% and 13%, respectively; margin width was not associated with disease-specific mortality but LR was a poor prognostic factor for survival (p = 0.003). Conclusion: Whilst negative margin provided local control over 90%, excellent local control was achieved with microscopic margins ≥2 mm. The role of margins is more important than radiotherapy in local control. Margins do not determine survival, but LR is associated with a poor prognosis.