Fig 4.

Multivariate Cox proportional hazards regression analysis of papillary thyroid cancer (PTC)–specific mortality risk with restricted cubic splines (RCS). Continuous linear association between patient age and PTC-specific mortality was observed (A) in the analysis of all patients and (B) even more significantly in patients with BRAF V600E, but (C) not in patients with wild-type BRAF. The blue line represents the fitted line of the association between patient age and the estimated hazard ratio (HR) of mortality after adjustment; the shaded region represents the 95% CI. The models were adjusted for the following clinicopathologic characteristics: patient sex, tumor size, extrathyroidal extension, lymph node metastasis, distant metastases, administered activities of radioactive iodine, and study center. The RCS plots were performed with the age of 45 years as the reference for HR calculation. (D) Specific HRs and 95% CIs are presented for the indicated patient age points. (*) Significantly different HRs in reference to patient age of 45 years.