Comparison of survival rates between papillary and follicular thyroid carcinomas among 36,725 patients.

Objectives: We sought to determine the impact of histologic subtype on disease-specific survival (DSS) in cases of differentiated thyroid carcinoma.

Methods: Adult patients with papillary thyroid carcinoma (PTC) or follicular thyroid carcinoma (FTC) were identified from the Surveillance, Epidemiology, and End Results (SEER) Database for the years 1988 to 2003. The patients were grouped according to tumor type (PTC or FTC), and their age, gender, tumor size and extension, and nodal or distant metastases were recorded. The Kaplan-Meier method was used to compare DSS rates on the basis of histologic subtype.

Results: We identified 36,725 patients, of whom 77% were female and 23% were male; PTC was diagnosed in 91% of patients, and FTC in the remaining 9%. Patients with PTC were younger, were more likely to be female, and had smaller tumors with higher rates of regional metastases but fewer distant metastases than FTC patients (p < 0.0001 for all). When the cases were stratified by stage, FTC patients had a worse DSS than did PTC patients for all stages - except for stages III/IVA and IVC among patients more than 45 years of age.

Conclusions: Follicular thyroid carcinoma portends a worse DSS than does PTC, even when the cases are controlled for stage. Consideration should be given to individual staging for these subtypes of differentiated thyroid carcinoma.