Bone invasion in soft tissue sarcomas of the extremities: An underappreciated prognostic factor. Bone invasion in soft tissue sarcomas

Background: Bone invasion is unfrequently reported in soft tissue sarcomas of the extremities (eSTS), it is difficult to assess preoperatively and its prognostic impact has not been extensively studied. The objective of this paper was to analyze the incidence and the clinical impact of histologically proven bone invasion in individuals with eSTS. Methods: A retrospective analysis was performed using the medical files patients who had eSTS and were treated between 2012 and 2016. A 5 years survival was estimated using the Kaplan-Meier method and a Cox proportional risk assessment. The outcomes of patients with and without bone invasion were compared. Results: 370 patients were included in the analysis. The median follow up was 25 months, the median age was 45 years (IQR 31-58). Bone invasion was found in 41 (11.08%). Median tumor size was 11.8 cm. The majority of individuals were diagnosed at stage IV (n = 116, 31.4%), followed by stage IIIB (n = 87, 23.5%). High histological grade was associated with worse OS (HR 2.23, CI 95% 1.36-3.65, p = 0.001). Absence of bone invasion was associated with better prognosis (HR 0.541, CI 95% 0.34-0.86, p = 0.009). OS was 27.3 vs 49.28 months. The disease-free survival (DFS) was 25.1 in bone invasion vs 45.23 without bone invasion. Conclusion: Bone invasion in individuals with eSTS is an independent adverse prognostic factor associated with lower OS and DFS; although infrequently reported, bone invasion might be considered as part of the staging in the future