Localized myxofibrosarcomas: roles of surgical margins and adjuvant radiotherapy
Menée en France à partir de données portant sur 425 patients atteints d'un myxofibrosarcome non métastatique de stade localisé traité par chirurgie entre 1996 et 2015 (âge médian : 66 ans ; durée médiane de suivi : 51 mois), cette étude évalue, du point de vue de la survie sans récidive, de la survie sans métastase et de la survie globale à 5 ans, l'intérêt d'une radiothérapie adjuvante en fonction de la qualité des marges de résection (R0 ou R1)
Background : The objective of this study was to describe the outcome and prognostic factors of adults treated for localized myxofibrosarcoma. Methods : We conducted a retrospective multicenter study of 425 non-metastatic patients (pts) operated between January 1996 and December 2015 in X national Group and were enrolled in the “Conticabase.” Pathological diagnosis was systematically reviewed by expert pathologists. The endpoints were relapse-free and metastasis-free survival. Log-rank tests and Cox models have been used to identified prognostic factors. Results : Median age was 66, 53% were males, 85% of cases occurred in limbs or superficial trunk, median size was 60 mm, 47%/39% had grade 2/3, 66% R0 resection and 34% R1 resection. Adjuvant radiotherapy was given to 65% of patients, neoadjuvant radiotherapy in 3%, neoadjuvant chemotherapy in 7% and adjuvant chemotherapy in 13%. The median follow-up was 51 months. The 5-year local relapse free-survival was 67%; independent prognostic factors for local relapse were R1 resection (HR=1.26; p=0.001) and adjuvant radiotherapy (HR= 0.35; p=0.0001) [i.e. R1 resection and no adjuvant radiotherapy increase the hazard ratio]. In stratified analysis, adjuvant radiotherapy was beneficial after R0 resection (p=0.0020) as well as after R1 resection (p=0.0001). The 5-year overall survival was 80%. The 5-year metastasis-free survival was 83%. Independent prognostic factors for metastatic relapse were: grade 3 (HR=1.975; p=0.0001) and size (HR=1.006; p=0.001). Conclusions : This large series of myxofibrosarcoma confirms the high rate of local relapse. Combination of R0 resection and adjuvant radiotherapy provided the best local control. In parallel with increasing rate of R0 resection and adjuvant radiotherapy, during the study we have observed a constant improvement of both metastatic and local relapse free survivals.