2.1.2. Outcome Analysis

Six to nine months after RAI therapy, the number of patients presenting without detectable Tg (stimulated Tg < 0.5 ng/mL) was comparable in both groups (77% in +mETE patients (106/138) and 81% in −mETE patients (258/317), *p*-value 0.262). Likewise, 97% of +mETE patients (134/138) and 99% of −mETE patients (313/317), *p*-value 0.241) did not present with relevant residual, cervical, or distant pathological uptake (*p*-value 0.387). Therefore, responder rates (combination of stimulated Tg < 0.5 ng/mL, no relevant uptake in the I-131 whole body scan, unremarkable neck ultrasonography) were similar in both groups (76% in +mETE patients (100/138) and 72% in −mETE patients (242/317), *p*-value 0.379). Furthermore, patients showed comparable responder rates irrespective of the histological subtype (*p*-value = 0.908). The outcome of the whole group is shown in Table 1.


**Table 1.** Patient characteristics and outcome analysis of the entire group.

mETE, minimal extrathyroidal extension; PTC, papillary thyroid carcinoma; T, tumor; N, nodus; RAI, radioactive iodine; GBq, gigabecquerel; Tg, thyroglobulin; TSH, Thyroid-stimulating hormone; WBS, whole body scan; responder rates: combination of stimulated Tg < 0.5 ng/mL, no relevant uptake in the I-131 whole body scan, unremarkable neck ultrasonography.

Both groups showed no significant differences in terms of age (57 ± 16 years in +mETE patients and 55 ± 14 in −mETE patients, *p*-value 0.504), sex (69% female in +mETE patients (95/138) and 74% in −mETE patients (234/317), *p*-value 0.276) and tumor size (14.9 ± 8.4 mm in +mETE patients and 14.4 ± 8.7 mm in −mETE patients, *p*-value 0.551).
