A multi-institutional validation study of prognostic nomograms for retroperitoneal sarcoma

Area of Science:

• Oncology
• Surgical Oncology
• Biostatistics

Background:

• Prognostic nomograms aid in predicting outcomes for patients with retroperitoneal sarcoma (RPS).
• Existing nomograms, including Sarculator and Memorial Sloan Kettering (MSK) sarcoma nomograms, require validation in contemporary patient cohorts.

Purpose of the Study:

• To validate the prognostic accuracy of the Sarculator and MSK sarcoma nomograms.
• To assess the performance of these nomograms in a large, multi-institutional cohort of primary RPS patients undergoing resection.

Main Methods:

• Retrospective analysis of 502 patients with primary RPS undergoing resection (2000-2017) across nine institutions.
• Calculation of predicted survival probabilities (7-year DFS/OS, 4/8/12-year DSS) using Sarculator and MSK nomograms.
• Comparison of predicted probabilities with observed outcomes using calibration plots and Harrell's concordance index (C-index).

Main Results:

• The cohort comprised diverse histologies, with leiomyosarcoma (30%) and liposarcoma variants (23%, 15%) being most common. Median tumor size was 14 cm, with Grade 3 tumors (56%) predominating.
• Sarculator nomogram achieved C-indices of 0.65 for 7-year DFS and 0.69 for 7-year OS, demonstrating good calibration.
• MSK nomogram achieved a C-index of 0.71 for 4-, 8-, and 12-year DSS, also showing good calibration.

Conclusions:

• Both the Sarculator and MSK nomograms demonstrated robust prognostic performance in a contemporary, multi-institutional cohort of resected primary RPS.
• These findings support the continued clinical use and adoption of these validated prognostic tools for retroperitoneal sarcoma management.