Risk Assessment of Visceral Sarcomas: A Comparative Study of 2698 Cases from the SEER Database.

Soft tissue sarcomas arising in visceral organs are rare and lack validated tumor-staging protocols. Clinicopathologic features and clinical outcomes of 2698 visceral sarcomas identified in the Surveillance, Epidemiology, and End Results Program (SEER) database were compared with sarcomas arising in the extremities/trunk (n = 10,237) or retroperitoneum (n = 1067) using standard statistical techniques. Important prognostic criteria for visceral sarcomas, as in other anatomic sites, included tumor size, histologic grade, and presence of metastatic disease. After adjustment for pertinent confounding factors, visceral sarcomas showed cancer-specific survival rates similar to those arising in the retroperitoneum but had worse outcomes than sarcomas in the extremities/trunk. Therefore, the prognostic performance of two different staging algorithms for retroperitoneal sarcomas was evaluated for their use in staging sarcomas of visceral organs. The current AJCC 8th edition and the recently derived Vanderbilt system for staging retroperitoneal sarcoma both showed adequate discrimination, as assessed by multiple clinical concordance indices, and no evidence of miscalibration. Therefore, the authors concluded that previously validated staging systems for retroperitoneal sarcomas based on conventional prognostic factors (histologic grade, tumor size, and presence of metastatic disease) are applicable to visceral sarcomas and should be incorporated into the next edition of the AJCC Cancer Staging Manual.