Tumor necrosis and clinical outcomes following neoadjuvant therapy in soft tissue sarcoma: A systematic review and meta-analysis

Background: The prognostic role of tumor necrosis following neoadjuvant therapy is established in bone sarcomas but remains unclear in soft tissue sarcomas (STS). Methods: We searched MEDLINE, MEDLINE in progress, EMBASE and Cochrane to identify studies that investigated neoadjuvant therapy in STS. Studies were required to report survival data based on extent of necrosis, or provided individual patient data allowing estimation thereof. Hazard ratios (HR) for relapse-free (RFS) and overall survival (OS) and odds ratios (OR) for recurrence at 3 years and for death at 5 years were pooled in a random effect meta-analysis. Associations between patient characteristics and attainment of >= 90% necrosis were explored. Results: 21 studies comprising 1663 patients were included. Extremity tumors were most common (n = 1554; 93%). Induction regimens included chemotherapy with radiotherapy (n = 924; 56%), chemotherapy alone (n = 412; 25%), radiotherapy alone (n = 78; 5%), isolated limb perfusion (ILP) (n = 231; 14%), and targeted therapy/radiotherapy (n = 18; 1%). Patients with < 90% necrosis had higher hazard of recurrence (hazard ratio [HR] 1.47; 95% CI: 1.06-2.04; p = 0.02) and death (HR 1.86; 95% CI: 1.41-2.46; p < 0.001). Risk of recurrence at 3 years (OR = 3.35; 95% CI: 2.27-4.92; p < 0.001) and of death at 5 years (OR 2.60; 95% CI: 1.59-4.26; p < 0.001) were similarly increased. Compared to other modalities, ILP was associated with higher odds of achieving >= 90% necrosis (OR 12.1; 95% CI: 3.69-39.88; p < 0.001). Conclusion: Tumour necrosis < 90% following neoadjuvant therapy is associated with increased recurrence risk and inferior OS in patients with STS.