Objective: To identify possible risk factors associated with persistent disease 5 years after total or near-total thyroidectomy in patients with differentiated thyroid cancer (DTC).
Patients and method: Retrospective study evaluating data from 63 patients 5 years after they were first diagnosed of DTC. At this time of the study, 46 subjects were considered disease-free (F group) whereas 17 had evidence of persistent disease or had died from DTC (P group). We compared both groups of patients regarding the following variables: a) variables at diagnosis related to the patient (age, gender) and the tumor (histological type, size, extrathyroidal involvement, vascular invasion, multifocality, lymph node and distant metastases), and b) variables recorded during follow-up: percentage of subjects showing serum stimulated thyroglobulin > or = 10 ng/ml few weeks postoperatively (Tg0) and 6 to 12 months later (Tg1).
Results: Male gender, extrathyroidal involvement and lymph node metastases were more frequent in P group than in F group (41 vs. 11%, 60 vs. 18% and 50 vs. 5.5%; p < 0.05). During the follow-up the percentage of patients showing Tg > or = 10 ng/ml was higher in P group compared to F group, both at a few weeks postoperatively and 6 to 12 months later (Tg0, 75 vs. 13%; Tg1, 69% vs. 0; p < 0,05).
Conclusions: In our patients, male gender, extrathyroidal involvement, and lymph node metastases at diagnosis were associated with persistent disease 5 years later. Serum stimulated thyroglobulin had a very high predictive value both just after surgery and in the next 6 to 12 months and could help identifying subjects who need a closer follow-up.