Prognostic factors for thyroid carcinoma

BACKGROUND: A number of prognostic factors for thyroid carcinoma have been identified, including sociodemographic characteristics, such as age and gender, and tumor characteristics, such as histology and stage. The relative importance of these factors as independent predictors of survival for patients with papillary, follicular, anaplastic, and medullary thyroid carcinoma has been extensively studied but remains uncertain. METHODS: The authors used data collected by the Surveillance, Epidemiology and End Results (SEER) program of the National Cancer Institute between 1973 and 1991 to investigate prognostic factors for each of the major histologic types of thyroid carcinoma in a population-based patient series and to assess the effect of these factors as predictors of survival. RESULTS: Both tumor and sociodemographic characteristics were independently associated with survival. Patients with papillary carcinoma had the highest 10-year relative survival (0.98), followed by those with follicular carcinoma (0.92) and medullary carcinoma (0.80). Anaplastic tumors had the lowest 10-year relative survival (0.13). Stage at diagnosis and differentiation status were strong independent prognostic factors for each histologic type. Advanced stage at diagnosis was a stronger prognostic factor for medullary carcinoma than for other histologic types. Increasing age was associated with lower relative survival for each histologic type. Gender, marital status, and ethnicity were significant, but weaker, predictors of survival. CONCLUSIONS: Survival varied markedly among patients with different histologic types of thyroid carcinoma. Stage at diagnosis and tumor differentiation were important prognostic factors for each histologic type. Age at diagnosis was a stronger predictor of survival for patients with follicular and medullary carcinoma than for patients with papillary carcinoma.