title: Factors related to mortality in patients with papillary and follicular thyroid cancer in long-term follow-up.
abstract: OBJECTIVE
  Differentiated thyroid cancer (DTC) includes papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC). They have different biological behavior but are frequently analyzed together in studies. We aimed to identify factors associated with mortality in those two different cancer subtypes.
  
  
  METHODS
  Case series study, with clinical-pathological analysis of the characteristics of 424 patients with PTC and 89 patients with FTC, correlating them to survival rates in a single institution.
  
  
  RESULTS
  Patients were followed from 1983 to 2011. Mean follow-up time was 9.4 years for FTC (range 1-36.6 years) and 6.8 years for PTC (range 1.1-30.7 years). Mean age at diagnosis was 51.2 ± 15.5 for FTC and 41 ± 14.7 years for PTC. 50.62% of FTC nodules sized 1.1-4 cm and 20% of PTC sized ≤1 cm. Cox multiple regression analysis evidenced distant metastasis at diagnosis (p = 0.0038; relative risk (RR) 41.247, 95% confidence interval (CI) 3.317-512.986), lymph node metastasis at diagnosis (p = 0.0081; RR 50.98, 95% CI 2.783-934.026) and vascular/lymphatic invasion (p = 0.0039; RR 40.424, 95% CI 3.287-497.177) as factors related to mortality in FTC patients. For PTC, the factors were distant metastasis at diagnosis (p < 0.0001; RR 32.5, 95% CI 6.676-158.543) and degree of differentiation (poor versus well differentiated, p = 0.003; RR 10.4, 95% CI 2.218-49.487).
  
  
  CONCLUSIONS
  The common factor that influenced mortality for FTC and PTC patients was distant metastasis at diagnosis, increasing mortality rate by 41 times in FTC and 30 times in PTC patients. The different factors influencing mortality for different DTC types highlight the importance of analyzing them separately.
authors.affiliation: Division of Endocrinology, Internal Medicine Department, University of Campinas, Rua Tessalia Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, SP, Brazil.
authors.forename: Thaís Gomes
authors.initials: TG
authors.lastname: de Melo
authors.forename: Denise Engelbrecht
authors.initials: DE
authors.lastname: Zantut-Wittmann
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Ficher
authors.forename: Lígia Vera Montalli
authors.initials: LV
authors.lastname: da Assumpção
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000175:diagnosis* / Q000401:mortality*; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000175:diagnosis* / Q000401:mortality*; D002291:Carcinoma, Papillary; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000401:mortality*; D013997:Time Factors