Background: The current dogma is a life-long follow-up for patients treated for follicular-derived differentiated thyroid cancers (DTC). Our primary objective was to determine the time to recurrence in a series of DTC patients with an excellent response to therapy 6 months after total thyroidectomy and radioiodine therapy. The secondary objectives were to determine the time to suspicion of recurrence and to identify factors associated with recurrence. Methods: This retrospective cohort study included patients treated for DTC between 2008 and 2012 and in remission 6 months after total thyroidectomy and radioiodine treatment. The criteria for remission were negative imaging and suppressed thyroglobulin (Tg) <0.2 ng/mL or rh-TSH-(recombinant human TSH) stimulated Tg <1 ng/mL according to the 2015 ATA (American Thyroid Association) guidelines. Recurrence was defined by cytologically and/or histologically proven cervical lymph node metastasis or the administration of a second radioiodine treatment. Results: Among 721 patients treated for DTC, 158 were excluded because of persistent disease at 6 months, 71 because of missing follow-up data, and 492 were included. The mean and median follow-up time were 7.0 and 7.9 years (interquartile range IQR [2.1-11.3]). Recurrence occurred for 7 patients (1.4%), 1 initially classified as high recurrence risk, 3 as intermediate, and 3 as low risk according to the 2015 ATA guidelines. All relapses occurred within 10 years after initial management (4 within the first 5 years). For patients with recurrence, rise in Tg and/or suspicious lymph nodes were detected in six out of seven cases in the first 8 years and for the last case 10 years after initial surgery. Conclusion: Low and intermediate recurrence risk DTC patients with excellent response 6 months after total thyroidectomy and radioiodine and in remission 10 years later have an extremely low recurrence risk. Follow-up might be undertaken by primary care providers from this time point. These discharge recommendations should be confirmed by further prospective studies.
Keywords: differentiated thyroid carcinoma; excellent response; follicular-derived; follow-up; recurrence; thyroid.