Older Age Significantly Affects Mortality of Patients with Papillary Thyroid Carcinoma Only When They Have High-Risk Features

Background Old age is a known prognostic factor for mortality in patients with papillary thyroid carcinoma (PTC). This study aimed to investigate the relationship between cause-specific survival (CSS) following PTC and the extent of old age. Methods We enrolled 4692 patients aged >= 55 years with PTC who underwent surgery between 1989 and 2009 at Kuma Hospital (median follow-up period 140 months). The presence of at least one of the following was used to classify the patients as high risk: (1) tumor sizes > 4 cm, (2) node metastasis >= 3 cm, (3) significant extrathyroid extension corresponding to T4a, (4) extranodal tumor extension, and (5) distant metastasis. T1N0M0 PTC was classified as low risk, and all other patients were classified as intermediate risk. We divided all patients into three categories based on age: 55-64, 65-74, and >= 75 years. Results One low-risk patient (0.04%), 18 intermediate-risk patients (1.5%), and 105 high-risk patients (9.4%) died of PTC, and CSS of high-risk patients was poorer than that of others (p < 0.0001). The CSS of low and intermediate-risk patients did not differ with age. However, CSS of high-risk patients became significantly poorer with advancing age (p = 0.0017 for 55-64 years vs. 65-74 years, and p = 0.0109 for 65-74 years vs. >= 75 years). Conclusions Advanced age has a significant prognostic impact on CSS only for high-risk patients with PTC.