Outcome of patients with differentiated thyroid cancer treated with empirical radioiodine therapy on the basis of Thyroglobulin Elevation Negative Iodine Scintigraphy (TENIS) syndrome without structural disease: a retrospective cohort study

Background For differentiated thyroid cancer (DTC) patients with thyroglobulin (Tg) elevation and negative iodine scintigraphy (commonly termed "TENIS" syndrome) after thyroidectomy, radioactive iodine (RAI) therapy, and thyroid-stimulating hormone (TSH) suppression therapy, empirical RAI therapy may be considered. However, the outcome data of TENIS syndrome without structural disease after empirical RAI therapy have not shown clear evidence of improvement in survival. We assessed the efficacy of such empirical RAI therapy in TENIS syndrome without structural disease and evaluated the progression-free survival (PFS). Methods A total of 80 papillary thyroid cancer (PTC) patients with TENIS syndrome without structural disease were included in this retrospective study. 52 patients were treated with empirical RAI therapy while another 28 patients were untreated. The progression-free survival (PFS) of both groups was defined as the main outcome. The secondary outcome was the comparison of serum Tg levels 12 months after being diagnosed as TENIS syndrome. Results The PFS of the empirical RAI therapy group was better than the untreated group ( p < 0.001). Moreover, there was significant difference in Tg normalization between patients treated with empirical therapy and without treatment ( p = 0.001). Empirical RAI therapy ( p = 0.001) predicts better PFS. Male gender ( p = 0.041) and empirical RAI therapy ( p = 0.002) predict better remission in serum Tg level. Conclusion Patients with TENIS syndrome without structural disease can benefit from empirical RAI therapy in both PFS and Tg normalization.