Differentiated thyroid carcinoma: a 5-years survival study at a referral hospital in Brazil

BACKGROUND: Although the prognosis of differentiated thyroid carcinoma (DTC) therapy is considered excellent over time, some cases have a poorer prognosis and evolve into death. OBJECTIVE: This study aimed to estimate the 5-year specific survival and to identify prognosis factors in a cohort of DTC adult subjects. METHODS: Survival probability was estimated by Kaplan-Meier’s method in a retrospective hospital-based cohort study. Comparisons were made by log-rank test. Prognosis factors were identified using Cox risk modeling and crude and adjusted Hazard Ratio measures were obtained. Two models were estimated, considering age grouping of the 7(th) and 8(th) editions of TNM. RESULTS: Specific 5-year survival in the cohort was 98.5% (95%CI: 94.2 – 97.5). Considering TNM 7(th) edition, the risk estimates were 9.88 (95%CI: 1.67 – 58.33) for age group ≥ 55 years, 18.87 (95%CI: 7.38 – 48.29) for individuals with distant metastasis, 6.36 (95%CI: 2.26 – 17.91) for patients who underwent lymphadenectomy and 0.16 (95%CI: 0.06 – 0.43) for those who received radioiodine therapy. For TNM 8(th) edition, the risk estimates were 10.12 (95%CI: 2.05 – 50.09) for age group ≥ 55 years, 12.43 (95%CI: 4.58 – 33.77) for individuals with distant metastasis, 5.06 (95%CI: 1.82 – 14.05) for patients who underwent lymphadenectomy and 0.19 (95%CI: 0.07 – 0.51) for those who received radioiodine therapy. CONCLUSIONS: This cohort had a very high survival over a 5-year period. The prognosis was negatively influenced by age, distant metastasis and lymphadenectomy, whereas radioiodine therapy was found to be protective.