The survival and prognosis analysis of synovial sarcoma subtypes: a Surveillance, Epidemiology, and End Results population-based analysis.

Purpose: By comparing epidemiologic and prognostic data of synovial sarcoma subtypes, this study aims to clarify the difference in prognosis and risk factors among different synovial sarcoma subtypes.

Methods: In total, 1692 patients with synovial sarcoma in the USA who were diagnosed during 1975 through 2016 and retrieved from the Surveillance, Epidemiology, and End Results (SEER) program were studied.

Results: There were statistically significant differences in the distribution of age and race among three synovial sarcoma subtypes, while no major differences in the distribution of sex, tumor stage, and tumour size were found. The highest five and ten year survival rates were found in the biphasic subtype (69%, 60%), followed by the monophasic subtype (59%, 49%), and lowest in the epithelioid subtype (32%, 26%). Age and SEER historic stage were the two demographic factors that found to have statistically significant impact on survival in all subtypes. Radiation was found to be protective in the monophasic subtype (HR 0.61, p < 0.001).

Conclusion: Among different synovial sarcoma subtypes, the biphasic subtype favoured the best survival, while the epithelioid cell subtype was associated with the worst. Male and black race were independently associated with worse survival only in the monophasic subtype. Radiotherapy could provide significant benefit for patients with the monophasic synovial sarcoma.