Endocrine Abstracts

Background: Clinical predictors of survival of radioiodine-refractory differentiated thyroid cancer (RR-DTC) are poorly described. Age has been identified as a major prognostic factor in differentiated thyroid cancer. We asked whether age was a valuable predictor of poor prognosis in RR-DTC.

Patients and method: This single centre, retrospective study enrolled all patients diagnosed with a RR-DTC between 1991 and 2017. The primary end point was overall survival. Secondary endpoint was progression free survival. Log-rank test was used to compare population.

Results: Between 1991 and 2017, 155 patients was diagnosed with a RR-DCT. Diagnosis of RR-DTC was done before the age of 65 (younger group) in 71 cases and in 84 cases after 65 years-old (older group). Mean follow-up was 50 months (1–231). During follow up, 75 patients died, 35 in younger group and 41 in older group. Median overall survival was 4.19 years for younger group and 4.22 years for older group, with no statistical difference (P=0.5). Progression free survival was 1.5 years in younger group and 0.98 years in older group, but without statistical difference (P=0.2). There was no difference between the two groups especially regarding sex, histological subtype, or number of distant metastases. Therapeutic management did not differ between the 2 groups. Forty eight patients received tyrosine kinase inhibitor (TKI), 20 (28%) in younger group and 28 (33%) in older group (P=0.5). There was also no difference for radiotherapy (P=0.6), cervical surgery (P=0.391) or local treatments (cementoplasty, radiofrequency, metastases’ surgery (Ps=ns)).

Conclusion: In RR-DTC patients, age was not predictive of the outcome. Continual progress made in the management of RR-DTC, especially in the last 15 years with the implementation of systemic therapies (i.e. TKI) should probably make reconsider the natural history and conventional prognostic factors of RR-DTC.