Differentiated thyroid carcinoma in the elderly: influence of age on disease-free and overall survival.

[PURPOSE] We investigated whether age at diagnosis of differentiated thyroid carcinoma (DTC) may be a risk factor for structural disease and mortality after primary treatment in aging patients.

[METHODS] A multicenter, retrospective analysis including patients older than 60 years at DCT diagnosis was designed. All subjects were treated by surgery with or without radioiodine adjuvant therapy and had a minimum follow-up of one year. We compared elderly patients (group 1, 60-74 years) with very old patients (group 2, ≥75 years).

[RESULTS] The study involved 1668 patients (74.3% women, median age 67 years, 87.6% papillary thyroid cancer, 73.3% treated with radioiodine), including 1397 in group 1 and 271 in group 2. Patients in group 2 had larger tumor size (1.8 [0.8-3.0] vs 1.5 [0.7-2.8] cm; P = 0.005), higher proportions of tumors with vascular invasion (23.8 vs 16.4%; P = 0.006), and lower proportion of lymphocytic thyroiditis (18.6 vs 24.9%; P = 0.013) than subjects in group 1. Kaplan-Meier survival analysis showed that patients in group 2 had significantly lower structural disease-free survival (DFS) and overall survival (OS) than patients in group 1 (P = 0.035 and <0.001, respectively). In multivariate Cox regression analysis, age was a risk factor significantly associated with OS. However, age was significantly associated with DFS in unadjusted analysis and in analysis adjusted by gender and risk classification variables, but not when pathological and therapy-related variables were introduced in the model. On the other hand, patients who received radioiodine had worse DFS (P < 0.001) compared to those who did not.

[CONCLUSION] Although age is a conditioning factor for OS, very old patients do not have a greater risk of developing structural disease throughout the follow-up than elderly patients with DTC.