The role of surgical margin quality in myxofibrosarcoma and undifferentiated pleomorphic sarcoma

Objectives: The effect of margin quality as a barrier against infiltration of soft-tissue sarcomas (STSs) has been unclear. We aimed to investigate the effect of margin quantity and quality on local control for myxofibrosarcoma (MFS) and undifferentiated pleomorphic sarcoma (UPS). Methods: 278 patients with a localised MFS and UPS were studied. Margin quality was categorized into five types; type 1, pseudocapsule/reactive zone; type 2, fat/fibrofatty tissue; type 3, muscle; type 4, fascia; type 5, periosteum. Results: The 5-year cumulative LR incidence was 22% and 13% in patients with positive and 0.1–9.9 mm margins, respectively, but decreased to 3% with ≥10.0 mm margins (p = 0.009); the cumulative LR incidence was significantly lower in patients with ≥10.0 mm margins than those with positive margins (p = 0.033) but was not significantly different in those with 0.1–9.9 mm margins (p = 0.183). In patients with 0.1–9.9 mm margins, the cumulative LR incidence was affected by margin quality; type 4 and 5 provided an LR risk less than 5% (p < 0.001), which was similar to those with margins ≥10.0 mm. Combining these two factors together, the LR risk in patients with positive or 0.1–9.9 mm margins without fascia/periosteum was approximately 11 × higher than patients with 0.1–9.9 mm margins with fascia/periosteum or margins ≥10.0 mm (p = 0.002). Conclusions: A resection margin of 0.1–9.9 mm with fascia or periosteum provided a similar LR risk profile to ≥10 mm margins with any margin quality, which provided the lowest LR risk. The quality of fascial or periosteal tissue margins may be equivalent to a margin quantity of 10 mm as a barrier to LR.