The enigma of myxofibrosarcoma of the extremity

Abstract

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.

Impact of infiltrative growth on the outcome of patients with undifferentiated pleomorphic sarcoma and myxofibrosarcoma

“…Although we have completed a pathological review of all tumor samples previously diagnosed as “malignant fibrous histiocytoma,” there were a relatively small number of patients with MFS. Additionally, there was no patient diagnosed as a grade 1 MFS, which was approximately 20% of whole MFS patients in the literature . Regarding the radiographic evaluation of growth patterns, MRI sequences were not uniform because of the retrospective nature of this analysis.…”

“…However, several lines of evidence indicates that UPS and MFS frequently present an infiltrative growth pattern histologically and radiographically, which might result in a relatively higher incidence of inadequate tumor resection . In addition, MFS shows a poor response to radiotherapy . Although these characteristic features of UPS and MFS might be associated with a poor local control, it has been as yet elusive whether there could exist a correlation between infiltrative growth and the oncological outcomes of UPS and MFS.…”

ASS1as a Novel Tumor Suppressor Gene in Myxofibrosarcomas: Aberrant Loss via Epigenetic DNA Methylation Confers Aggressive Phenotypes, Negative Prognostic Impact, and Therapeutic Relevance

“…Myxofibrosarcomas are characterized by increased metastasis after relentless local recurrence (1)(2)(3). Such a recurrence has been shown to parallel the cytogenetic complexity and eventually lead to metastasis (4,5).…”

“…Such a recurrence has been shown to parallel the cytogenetic complexity and eventually lead to metastasis (4,5). The overall survival rate in patients with a myxofibrosarcoma is approximately 75% at 5 years, and several series have provided conflicting data for clinicopathologic prognosticators (1,3,4,6,7). We and others have addressed the importance of clear margins, which predicted better local control and translated into survival benefits (1,7).…”

High-Grade Extremity Myxofibrosarcoma with Synchronous Mesenteric Leiomyosarcoma: Double Primary Sarcomas

“…MFS is one of the most common sarcomas in the extremities of elderly patients [8]. It arises more frequently in subcutaneous tissues than in deep soft tissues [9].…”