Survival Analysis of Papillary Thyroid Carcinoma in Relation to Stage and Recurrence Risk: A 20-Year Experience in Pakistan.

OBJECTIVE

The aim of this study was to evaluate the overall and progression-free survival of papillary thyroid carcinoma (PTC), comparing the American Thyroid Association (ATA) guideline for risk of recurrence with the TNM staging system with dynamic assessment at 2 years.

PATIENTS AND METHODS

This study is a retrospective analysis of 689 PTC patients over a 20-year period at a single center. Disease-free survival based on the TNM staging and ATA recurrence risk was calculated using Kaplan-Meier curves. Dynamic response assessment during the first 2 years was compared for both systems. Survival was calculated based on age, baseline resectability, and postthyroidectomy serum tumor marker levels.

RESULTS

Six hundred eighty-nine (72.2%) of the total thyroid cancer patients had PTC. Four hundred sixty-nine patients were females, and 220 patients were males. The age range was 6 to 87 years. Five hundred thirty-five patients were resectable, and 56 patients were unresectable. One hundred fifty-one patients were excluded due to insufficient information on recurrence risk. By ATA categorization, 39% had low risk, no disease-related mortality; 44% had intermediate risk, 3 died; and 17% had high risk, 32 died. The 5-year disease-free survival was 54%, 26%, and 5% in low-, intermediate-, and high-risk groups, respectively. The log-rank test showed a significant difference in the percent survival (P < 0.01). TNM stage wise, in terms of survival, 1.3% in stage I, 2.2% in stage II, 0% in stage III, and 37.5% in stage IV died. The 20-year disease-free survival showed the following: stage I, 43%; stage II, 28%; stage III, 18%; and stage IV, 2%. There is significant difference in survival rate (P < 0.01). Both ATA risk classification and TNM staging were significant predictors of disease-free survival. On bivariate analysis, ATA classification (hazards ratio, 2.1; 95% confidence interval, 1.64-2.67; P = 0.001) was better predictive of overall survival versus TNM classification (hazards ratio, 1.3; 95% confidence interval, 1.11-1.43; P = 0.063).

CONCLUSIONS

The ATA risk stratification and continuous reassessment during the first 2 years predicts disease-free survival better than the TNM staging. Age older than 45 years, unresectable disease, and elevated postthyroidectomy thyroglobulin levels dictate a poorer prognosis.