Empirical Radioiodine Therapy Improves Progression-Free Survival in Thyroglobulin Elevation Negative Iodine Scintigraphy (TENIS) Syndrome Without Structural Disease

Introduction: 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 136 patients with TENIS syndrome without structural disease were included in this retrospective study and divided into the empirical RAI therapy group and the untreated group. Patients in the empirical RAI therapy group received RAI therapy (5.00-7.70 GBq), while the untreated group continued to follow up. The progression-free survival of both groups was defined as the main outcome. Secondary outcomes were: the comparison of serum Tg level 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 the two groups (P= 0.025). Empirical RAI therapy(P<0.001) and fewer metastatic lymph nodes(LNMs) (P=0.022) predict the better PFS. Male gender(P=0.006) and empirical RAI therapy (P=0.007) predict better remission in serum Tg level.

Conclusions: Patients with TENIS syndrome without structural disease can benefit from empirical RAI therapy in both PFS and Tg normalization.