To describe the clinico-pathological features of 23 patients affected by primary PS and LMS of bone, to confirm the diagnosis by molecular analysis, to evaluate the clinical outcome and to explore the prognostic impact of these features on disease-free (DFS) and overall survival (OS).
Primary PS and LMS of bone surgically treated from 2004 to 2015 were retrospectively reviewed. We analysed: age, sex, stage, histotype, histological-grade and surgical and/or medical therapy. IDH1 mutational status was evaluated and immunohistochemical staining was performed for smooth muscle actin and desmin. For molecular analysis tumor DNA was extracted from freshly cut FFPE sections by GeneRead™ DNA FFPE (Quiagen) and ddPCR (Bio-rad) was used to determine the presence of IDH1H and IDH1C mutations. DFS and OS rates were calculated according to the Kaplan-Meier method. The differentiation (myogenic, MD, versus non-myogenic, NMD) was correlated with the outcome using Kaplan-Meier method.
23 patients with primary PS or LMS of bone were included in the study. Median age was 49 years (range 13-90), male/female 14/9, 18 had localised disease and 5 metastatic disease, 17 received surgery, 14 received adjuvant therapy, 1 received neoadjuvant chemotherapy and 5 received up-front chemotherapy for advanced disease. All cases were histologically and radiologically reviewed: 17 PS and 6 LMS were identified. All cases were high-grade (FNCLCC grading system). Mutational analysis is currently underway and it will be presented at the meeting. 5-year OS of the whole series was 60% (95% CI; 3,1 – NE) and 5-year DFS was 50% (95% CI; 1,6 – 12,2). Patients with advanced disease are 13: 5-year OS in this subgroup was 38% (95% CI; 2,5 – NE). We identified MD in 11 cases. There were no significant differences between the MD and NMD groups in terms of DFS (logrank p-value=0,6788) and OS (logrank p-value=0,7389).
These primary malignant bone tumours are very rare with poor prognosis after relapse or when radical surgery is not feasible. MD did not predict a worse outcome than NMD in terms of OS and DFS.
Clinical trial identification
Legal entity responsible for the study
Giacomo Giulio Baldi
All authors have declared no conflicts of interest.