Survival nomogram for osteosarcoma patients: SEER data retrospective analysis with external validation

This study aimed to develop a nomogram based on the clinicopathological factors affecting the prognosis of osteosarcoma patients to help clinicians predict the overall survival of osteosarcoma patients. A total of 1362 patients diagnosed with osteosarcoma were enrolled in this study, among which, 1081 cases were enrolled from the SEER (Surveillance, Epidemiology, and End Results) database as training group, while 281 patients from two Clinical Medicine Center database were used in validation group. Univariate and multivariate Cox analyses were performed to identify the independent prognostic factors for overall survival. Nomogram predicting the 3- and 5-year overall survival probability was constructed and validated. Multiple validation methods, including calibration plots, consistency indices (C-index), and area under the receiver operating characteristic curve (AUC) were used to validate the accuracy and the reliability of the prediction models. Decision curve analysis (DCA) was conducted to validate the clinical application of the prediction model. Furthermore, all patients were divided into low- and high-risk groups based on their nomogram scores. Kaplan-Meier (KM) curves were applied to compare the difference in survival between the two groups. Predictors in the prediction model included age, sex, tumor size, primary site, grade, M stage, and surgery. Our results showed that the model displayed good prediction ability, and the calibration plots demonstrated great power both in the training and the validation groups. In the training group, C-index was 0.80, and the 3- and 5-year AUCs of the nomogram were 0.82 and 0.81, respectively. In the validation group, C-index was 0.79, and the 3- and 5-year AUCs of the nomogram were 0.85 and 0.83, respectively. Furthermore, DCA data indicated the potential clinical application of this model. Therefore, our prediction model could help clinicians evaluate prognoses, identify high-risk individuals, and provide individualized treatment recommendation for patients with osteosarcoma.