[Influencing factors for differentiated thyroid cancer with distant metastasis and construction of a risk prediction...

Objective: To analyze the risk factors for differentiated thyroid cancer(DTC) with distant metastases and establish a suitable prognostic risk prediction model. Methods: A retrospective analysis was performed on the clinical data of 2 337 patients diagnosed with distant metastasis of DTC from January 2000 to December 2021, as recorded in the Surveillance, Epidemiology, and End Results (SEER) database. Using the sample function in R, patients were randomly divided into a training set (n=1 635) and an internal validation set (n=702) at a ratio of 7∶3. Additionally, 227 patients with DTC and distant metastasis from Tianjin Medical University Cancer Institute and Hospital between January 2010 and December 2021 were included as an external validation set. Univariate and multivariate Cox proportional hazards regression model analysis, least absolute shrinkage and selection operator (LASSO) regression analysis were employed to screen for prognostic factors affecting the outcomes of patients with DTC and distant metastasis, and a prognostic prediction model nomogram was constructed. The predictive ability, accuracy, and clinical applicability of the model were evaluated using the area under the receiver operating characteristic curve (AUC), calibration curves, and decision curve analysis (DCA). Results: A total of 2 337 patients with distant metastasis of DTC were retrieved from the SEER database, including 988 males and 1 349 females, with the age of (58.4±18.6) years. Among them, 1 254 patients died with a median overall survival (OS) time of [M (Q₁, Q₃)] 42.0 (13.0, 95.0) months. At Tianjin Medical University Cancer Institute and Hospital, a total of 227 patients with DTC accompanied by distant metastasis were included, comprising 62 males and 165 females, with the age of (56.7±16.8) years. Among these patients, 114 died with a median OS time of 43.0 (15.0, 101.0) months. The follow-up ended upon the patient's death or March 31, 2025. After analysis using a univariate Cox proportional hazards regression model and screening via LASSO regression, 4 variables were included from the training set, including age, maximum tumor diameter, invasion of vital tissues, and surgical treatment. Multivariate Cox proportional hazards regression model analysis showed that age≥55 years (HR=3.37, 95%CI: 3.08-4.53), maximum tumor diameter>4 cm (HR=1.83, 95%CI: 1.12-2.99), and invasion of vital tissues (HR=2.15, 95%CI: 1.81-2.56) were risk factors affecting the OS of patients with DTC accompanied by distant metastasis, while surgical treatment (HR=0.44, 95%CI: 0.36-0.53) was a protective factor. A prognostic prediction model for patients with DTC accompanied by distant metastasis was constructed using these influencing factors. The AUC for predicting 3, 5, and 10 year OS were 0.780 (95%CI: 0.754-0.805), 0.769 (95%CI: 0.743-0.795), and 0.836 (95%CI: 0.809-0.864)(in the training set); 0.804 (95%CI: 0.768-0.841), 0.815 (95%CI: 0.779-0.850), and 0.877 (95%CI: 0.844-0.911)(in the internal validation set); and 0.753 (95%CI: 0.682-0.824), 0.717 (95%CI: 0.642-0.792), and 0.810 (95%CI: 0.725-0.894)(in the external validation set). The calibration curves demonstrated good fit between the predicted and observed values (all P>0.05), and DCA indicated that the model had high clinical application value. Conclusions: Age≥55 years, maximum tumor diameter>4 cm, and vital tissue invasion are independent risk factors for poor survival in patients with metastatic DTC, whereas surgical treatment improves prognosis. The proposed nomogram provides reliable prognostic assessment and may support individualized risk stratification and clinical decision-making.