Comparative analysis of bone and soft tissue vs. visceral synovial sarcoma: Demographic, clinical, and survival outcomes; a retrospective population-based study.

Background: Synovial sarcoma (SS) is typically diagnoses in young adults and usually appears in the extremities and soft tissues. However, it can sometimes arise in visceral organs. This study examines the differences in patient demographics, clinical features, and survival rates between soft tissue and visceral synovial sarcoma.

Methods: We analyzed data from the Surveillance, Epidemiology, and End Results (SEER) database spanning 2000-2018. ANOVA (analysis of variance) was used to identify significant factors for multivariate analysis. Cox regression modeling was used to determine independent risk factors for survival.

Results: Of the 2,776 SS patients included, the median age was 39.0 years, predominating male (53.0 %) and white (81.3 %). Bone and soft tissue sarcomas were more common, accounting for 86.4 % of cases (p-value<0.001), while the rest were diagnosed as visceral sarcomas. Visceral SS patients were typically older (p-value<0.001), male (56.8 %), and white (84.8 %). They also presented more frequently with distant metastasis (HR 3.8, 95 % CI, 2.4-6.1), had larger tumors on average (HR for tumors >10 cm: 2.9, 95 % CI, 2.0-4.1), and were less likely to undergo surgery (HR 0.4, 95 % CI, 0.3-0.6). Despite receiving multimodal treatments, including surgery, radiation, and/or chemotherapy, visceral SS patients exhibited poorer overall survival compared to their bone and soft tissue SS counterparts (p-value<0.001).

Conclusion: Visceral SS often presents in older patients with advanced-stage and larger tumor size as compared to bone and soft tissue SS, which likely contributes to poorer survival. Advanced age, regional spread, and larger tumor size were all found to worsen outcomes, while surgery and radiation were found to be protective factors.