ORIGINAL ARTICLE Predictors for papillary thyroid cancer persistence and recurrence: a retrospective analysis with a 10-year follow-up cohort study Taciana Padilha de Castro* , †, William Waissmann†, Tayn~ ana C esar Sim~ oes‡, Rossana Corbo R. de Mello* , § and Denise P. Carvalho* , ¶ *Department of Endocrinology, Medical School, Federal University of Rio de Janeiro – UFRJ, †Research Center for Health Work and Human Ecology – CESTEH-ENSP/FIOCRUZ, ‡Department of Epidemiology and Quantitative Methods in Health – DEMQS- ENSP/FIOCRUZ, §Cancer Hospital 1, National Institute of Cancer INCA, and ¶Carlos Chagas Filho Institute of Biophysics – IBCCF/UFRJ, Rio de Janeiro, RJ, Brazil Summary Objective We aimed to determine outcome predictors of papil- lary thyroid cancer (PTC) persistence and recurrence, separately. Context The factors contributing to either persistence or recur- rence of PTC are poorly defined, as both outcomes are usually evaluated together. Design and patients In this 10-year follow-up cohort study, 190 PTC patients were evaluated (18–85 years old; registered from 1 January 1990 to31 December 1999 at a Brazilian Cancer Care referral Hospital). After initial surgery, we examined persis- tence (disease detected up to 1 year), recurrence (disease detected after 1 year) and PTC-free status (disease absence dur- ing follow-up). Measurements Outcome predictors were modelled using multinomial logit regression analysis. Results The univariate analysis showed that persistence and recurrence were significantly associated with lymph node metasta- sis (OR = 12Á33; OR = 2Á84, respectively), local aggressiveness (OR = 5Á22; OR = 3Á35) and extrathyroidal extension (OR = 5Á07; OR = 7Á11). Persistence was associated with male sex (OR = 3Á49), age above 45 years old at diagnosis (OR = 1Á03), macroscopic lymph node metastasis (OR = 5Á85), local aggressive- ness (OR = 5Á22), each 1-cm tumour size increase (OR = 1Á34), a cancer care referral hospital as the place of initial surgery (OR = 2Á3), thyroidectomy or near total thyroidectomy (OR = 3Á03) and neck dissection (OR = 3Á19). Recurrence was associated with the time of radioactive iodine ( 131 I) therapy (OR = 3Á71). After data modelling, persistence was associated with macroscopic lymph node metastasis (OR = 6Á17), 1-cm increases in tumour size (OR = 1Á30) and thyroidectomy or near total thyroidectomy (OR = 3Á82), while recurrence was associated with surgery at referral hospital (OR = 3Á79). Conclusions The best predictors of persistence were tumour size and macroscopic lymph node metastasis; when the initial surgery is of quality, the recurrence depends more on tumour’s biology aspects. (Received 1 October 0015; returned for revision 25 January 2016; finally revised 25 January 2016; accepted 26 January 2016) Introduction Predictors are used to support medical decisions regarding the initial treatment and the clinical follow-up for papillary thyroid cancer (PTC). 1–4 In the past, the analyses were fundamentally focused on predictors for mortality; 1,5 however, the staging sys- tems have improved for estimating PTC persistence and recur- rence, which are two major concerns regarding treatment. 4,6–8 Usually, the outcome predictors for PTC do not estimate persis- tence and recurrence independently. However, predicting each outcome individually would provide additional information to facilitate tailored treatment. Although one French study analysed predictors for PTC persistence and recurrence separately, 9 we have not found any other similar studies. A properly designed and reported outcome predictor study is of interest, mainly due to the fact that the identification of fac- tors that predict PTC relapse within the first year of follow-up might be useful to ameliorate clinical care. 10 To overcome the current limitations, our study aims to assess predictors for per- sistence separately from recurrence, based on data collected dur- ing initial treatment. Subjects and methods Study design characteristics and hospital setting We conducted a hospital-based cohort study of PTC patients registered at a tertiary hospital in Brazil, which is a centre of excellence in cancer care that offers complex diagnostic and therapeutic capabilities. The hospital is part of the National Correspondence: Denise P. Carvalho, Av Carlos Chagas Filho, 373, CCS, Bloco G, UFRJ, Cidade Universit aria, Ilha do Fund~ ao, 21941-902 Rio de Janeiro, RJ, Brazil. Tel.: +55 21 39386552; Fax: +55 21 22808193; E-mail: dencarv@biof.ufrj.br © 2016 John Wiley & Sons Ltd 1 Clinical Endocrinology (2016) doi: 10.1111/cen.13032