Development and Validation of the Nomograms for Prognostic analysis in Patients With extremity Synovial Sarcoma

Abstract Background Extremity Synovial Sarcoma (SS) is a rare and highly malignant disease with a poor prognosis. This study aimed to determine the main factors affecting the prognosis and survival of patients with extremity SS and predict the overall survival (OS) and cancer-specific survival (CSS) by establishing a predictive model. Methods The Surveillance, Epidemiology, and End Results (SEER) database was used to screen patients who were diagnosed with extremity SS from 2004 to 2015. Univariate and multivariate Cox regression analyses were used to identify the clinical risk factors, and a prognostic nomogram was established to predict the 5- and 10-years OS and CSS. Results A total of 811 patients with extremity SS were divided into training cohort (n = 406) and validation cohort (n = 405) cohorts. Based on the results of data analysis, we found that age, sex, primary site, chemotherapy, surgery, Radiation and SEER stage were independent risk factors for OS and CSS in patients with extremity SS and used them to construct the prognostic nomogram. In the training cohort, the C-indexes of the nomogram were 0.752 (95% CI: 0.717–0.787) and 0.772 (95% CI: 0.735–0.809) for predicting OS and CSS, respectively. In the validation cohort, the corresponding C-indexes were 0.754(95% CI: 0.719–0.789) and 0.779 (95% CI: 0.742–0.816), respectively. The results of the calibration curves of OS and CSS in the training and validation cohorts proved that the 5-year and 10-year survival time were consistent with the survival time predicted by the nomogram. Conclusions age, sex, primary site, chemotherapy, surgery, Radiation and SEER stage were independent prognostic risk factors in patients with extremity SS. Compared with the SEER stage model, our nomogram model that we established had more advantages.