The U-shaped association between age at diagnosis and recurrence in patients with papillary thyroid carcinoma: A retrospective single-institution cohort study

Purpose: Age is a significant predictor of papillary thyroid carcinoma (PTC). At present, the available evidence shows that age at diagnosis has an important impact on the recurrence of PTC. The objective of our investigation was to examine the relationship between age at diagnosis and recurrence in patients with PTC. Methods: The medical records of patients with PTC who were treated between January 2010 and December 2018 at a single institute in a cancer referral center in China were retrospectively reviewed. The hazard ratios (HRs) and 95 % confidence intervals (CIs) for recurrence-free survival (RFS), locoregional recurrence-free survival (LRRFS) and distant metastasis-free survival (DMFS) were assessed using Cox proportional hazard models and restricted cubic splines (RCSs). Results: A total of 13758 patients were included in the study. With a median follow-up of 60 months (range 12-277), a total of 687 patients experienced recurrence, and 90 patients died. The 5-year RFS, LRRFS and DMFS rates were 95.0 % (95 % CI 94.6%-95.4 %), 95.8 % (95 % CI 95.4%-96.2 %) and 98.8 % (95 % CI 98.6%-99.0 %), respectively. The adjusted smooth RCS curves revealed a U-shaped association between age at diagnosis and RFS, LRRFS, and DMFS. After adjusting for potential confounding variables, both younger (<= 30 years) and older (>= 55 years) patients exhibited significantly lower RFS and LRRFS rates than did middle-aged patients (31-54 years). Older patients had significantly lower DMFS rates. Conclusions: This study confirmed a U-shaped association between age at diagnosis and the risk of both locoregional recurrence and distant metastasis.