Initial Evaluation of Therapy Response after Adjuvant Radioiodine Therapy in Patients with Early-Stage Papillary Thyroid Cancer—Does Time Matter?

SIMPLE SUMMARY: In recent years, there has been a clear trend toward personalized therapy procedures in patients with thyroid cancer with the aim to avoid unnecessary overtreatment of patients and to ensure an improved quality of life. We confirmed that early diagnostic control at 6 months after initial radioiodine therapy shows no significant disadvantages compared to a delayed control after 9 months. Further, it was observed that patients stimulated by hormone withdrawal before radioiodine therapy had significantly better outcomes compared to patients stimulated exogenously with recombinant human thyroid-stimulating hormone (rhTSH). However, early diagnostic control after TSH stimulation represents the most balanced solution for the patient, specifically regarding hypothyroidism symptoms after hormone withdrawal. ABSTRACT: Background: The aim was to assess ablation success after initial radioiodine (RAI) therapy in early-stage PTC patients and compare outcomes of first diagnostic control after 6 and 9 months (6m/9m-DC) to examine whether time could possibly avoid unnecessary overtreatment. Methods: There were 353 patients who were matched regarding age, sex, and tumor stage and divided in two groups depending on time of first DC (6m- and 9m-DC). Therapy response was defined as thyroglobulin level <0.5 ng/mL, no pathological uptake in the diagnostic I-131 whole-body scintigraphy (WBS), and no further RAI therapy courses. The 6m-DC group was further divided into endogenously and exogenously stimulated TSH before RAI therapy and compared regarding outcome. Results: No significant differences were found between 6m-DC vs. 9m-DC regarding I-131 uptake in WBS (p = n.s.), Tg levels (p = n.s.), re-therapy rates (p = n.s.), and responder rates (p = n.s.). Significantly less relevant pathological I-131 uptake was found in WBS (p = 0.006) in endogenously compared to exogenously stimulated 6m-DC patients, resulting in lower re-therapy (p = 0.028) and higher responder rates (p = 0.001). Conclusion: DC at 6 months after RAI therapy and stimulation with recombinant human thyroid-stimulating hormone (rhTSH) represent the most balanced solution. Particularly regarding quality of life and mental relief of patients, early DC with rhTSH represents sufficient and convenient assessment of ablation success.