Limitations of Currently Available Sarcoma Prediction Tools in a Large Contemporary Upper Extremity Soft Tissue Sarcoma Cohort.

Soft tissue sarcomas (STS) of the upper extremity (UE) are rare but can lead to devastating outcomes. The Memorial Sloan Kettering Cancer Center (MSKCC) nomogram, Sarculator, and PERSARC predict local recurrence (LR), distant metastases (DM), and overall survival (OS) in extremity STS. We retrospectively reviewed 211 UE STS patients (2012-2022) at a single tertiary center, recording demographics, tumor factors, treatments, and outcomes. External validation employed concordance indices (C). The mean clinical follow-up was 4.9 years. Ninety-three patients (44%) presented after unplanned excision, and 168 patients (80%) underwent neoadjuvant or adjuvant therapy. LR occurred in 49 patients (23%), and DM in 47 patients (22%). Thirty-five patients (17%) expired at an average of 41.0 months post-presentation. C-indices for MSKCC nomograms were 0.28 (0.08, 0.52) and 0.30 (0.10, 0.54) for 3- and 5-year LR. C-indices for Sarculator were 0.64 (0.54, 0.73) and 0.63 (0.54, 0.72) for 5- and 10-year DM and 0.79 (0.67, 0.89) and 0.79 (0.67, 0.89) for 5- and 10-year OS. C-indices for PERSARC were 0.70 (0.59, 0.80) for 5-year LR and 0.81 (0.68, 0.91) for 5-year OS. Prognostic tools may underperform in UE STS due to small development cohorts and unique tumor characteristics.