Dynamic estimates of survival in patients with follicular thyroid cancer: a retrospective cohort study

Abstract

Background: Few studies have been conducted on the dynamic survival rates of follicular thyroid cancer (FTC). This study aimed to ascertain how the survival probability of patients with FTC changes over time.

Methods: In this retrospective analysis, 10,617 patients diagnosed with FTC between 2000 and 2019 from the Surveillance, Epidemiology, and End Results (SEER) database were included. Actuarial disease-specific survival (DSS) was estimated using the Kaplan-Meier method, and the log-rank test was used for comparisons. The annual hazard of mortality was determined using the hazard function, and the conditional survival (CS) was calculated using the life table method.

Results: A total of 459 (4.3%) patients died of FTC, and the 5-year and 10-year DSS rates were 96.6 ± 0.2% and 94.6 ± 0.3%, respectively. There was a statistically significant difference in the DSS rate between patients with different SEER combined summary stages (P < 0.001). The annual hazard curve for cancer mortality in the entire study cohort displayed a steep downward trend with a slight peak at 2.5 years after diagnosis, followed by a gradual decline. Patients with distant metastases exhibited a higher mortality hazard curve and more notable declining trend. CS demonstrated an upward trend across the entire study population, with the most pronounced trend in patients with distant metastases.

Conclusion: Prognosis improved over time in a stage-dependent manner in patients with FTC after diagnosis. The most significant improvement was observed in the patients with distant metastases. Notably, dynamic survival estimations, such as death hazard and conditional survival analysis, provide more precise survival projections than traditional survival analysis for FTC survivors.

Keywords: Annual hazard; Conditional survival; Follicular thyroid cancer; Prognosis.