Background
The reported high rate of local recurrence (LR) in myxofibrosarcoma raises the question of whether this sarcoma histology should be considered radioresistant. We compared rates and patterns of LR of high-grade (HG) myxofibrosarcoma to HG leiomyosarcoma, chosen due to similarity in incidence and general treatment approach.
Methods
202 patients with primary non-metastatic extremity myxofibrosarcoma (n = 114) and leiomyosarcoma (n = 88) underwent limb-sparing surgery and were prospectively followed. All 202 patients had HG tumors; 138 (68%) received adjuvant radiotherapy.
Results
The groups were comparable in age, sex, and chemotherapy use. Compared with leiomyosarcoma, myxofibrosarcoma presented more frequently with tumors >5 cm (p < 0.001), deep location (p = 0.036), and upper extremity site (p = 0.015). In addition, rates of positive/close margins (p < 0.001) and use of RT (<0.001) were significantly higher in myxofibrosarcoma. The 5-year overall LR rate was not significantly different according to histology: 14.6% for myxofibrosarcoma, 13.2% for leiomyosarcoma (p = 0.594). The only predictor of LR for the whole cohort of patients was positive/close margins (p = 0.01). Of 17 myxofibrosarcoma LRs, 8 (47%) occurred out of field, vs 1 of 12 (8%) leiomyosarcoma LRs (p=0.04). Leiomyosarcoma more commonly recurred distantly (54.1 vs 24.3% at 5 years, p=0.014)
Conclusion
Despite more adverse clinical features, myxofibrosarcoma recurred less often distantly than leiomyosarcoma whereas the LR rate was comparable between the two groups, suggesting that adjuvant RT is effective in myxofibrosarcoma. Myxofibrosarcoma LRs more commonly occurred out of field. Reduction in radiation-field margins may not be advisable in myxofibrosarcoma.