Predictors for papillary thyroid cancer persistence and recurrence: a retrospective analysis with a 10-year follow-up cohort study

ObjectiveWe aimed to determine outcome predictors of papillary thyroid cancer (PTC) persistence and recurrence, separately. ContextThe factors contributing to either persistence or recurrence of PTC are poorly defined, as both outcomes are usually evaluated together. Design and patientsIn this 10-year follow-up cohort study, 190 PTC patients were evaluated (18-85years old; registered from 1 January 1990 to31 December 1999 at a Brazilian Cancer Care referral Hospital). After initial surgery, we examined persistence (disease detected up to 1year), recurrence (disease detected after 1year) and PTC-free status (disease absence during follow-up). MeasurementsOutcome predictors were modelled using multinomial logit regression analysis. ResultsThe univariate analysis showed that persistence and recurrence were significantly associated with lymph node metastasis (OR=1233; OR=284, respectively), local aggressiveness (OR=522; OR=335) and extrathyroidal extension (OR=507; OR=711). Persistence was associated with male sex (OR=349), age above 45years old at diagnosis (OR=103), macroscopic lymph node metastasis (OR=585), local aggressiveness (OR=522), each 1-cm tumour size increase (OR=134), a cancer care referral hospital as the place of initial surgery (OR=23), thyroidectomy or near total thyroidectomy(OR=303) and neck dissection (OR=319). Recurrence was associated with the time of radioactive iodine (I-131) therapy (OR=371). After data modelling, persistence was associated with macroscopic lymph node metastasis (OR=617), 1-cm increases in tumour size (OR=130) and thyroidectomy or near total thyroidectomy (OR=382), while recurrence was associated with surgery at referral hospital (OR=379). ConclusionsThe 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.