Background: CV-PTC is often indolent with excellent long-term response, while TCV-PTC (≥50% of tall cells) have aggressive features and worse clinical behavior. Less is known about the clinical behavior of CV-PTC with tall cells <50% (TC/CV-PTC) that, so far, is considered as low risk tumor.
Aim: To evaluate the histological presentation of CV-PTC, TC/CV-PTC, TCV-PTC and their clinical behavior after 6 years of follow up.
Methods: We evaluated the data of 610 consecutive patients affected by PTC, divided in: group A (CV-PTC; 417/61068.4%), group B (TC/CV-PTC; 64/61010.5%) and group C (TCV-PTC; 129/61021.1%).
Results: No difference in gender, tumor dimension, multifocality, bilaterality, histological thyroiditis, central compartment lymph node dissection, pN1, number of metastatic lymph nodes and prevalence of 131I avid metastases at RRA, was found among the groups. Patients of group C were significantly older (P=0.02). Neoplastic emboli were more frequent in group B (23.4%) vs C (13.2%) and A (9.8%), while mETE in group C (73.6%) vs B (57.8%) and A (39.6%) (P<0.01). Low risk were prevalent in group A (50.4%) vs B (20.3%%) and C (0%) and Stage I was more frequent in group A (94.7%) and B (96.9%) vs C (82.2%) (P<0.01). In group A (87.1%), most patients were treated with lower activities of 131I (30 mCi) vs B (79.7%) and C (74.4%) (P<0.01). After 6 years, 18/610 (2.9%) were lost at follow up and the remaining were re-evaluated. No differences were found when considering excellent (ER) and indeterminate response (IR), while biochemical incomplete (BiR) was more frequent in group A (6.1%) vs C (4%) and B (1.6%), but above all, structural incomplete (StR) was more frequent in group B (13.1%) vs C (8.9%) and A (4.9%) (P<0.01). This difference is remarkable for CV/TC-PTC with tall cells 2040% (14.5%) while CV/TC-PTC with tall cells <10% showed no StR. Moreover, no differences were shown in re-treatments performed during the follow up (i.e. surgeries or 131I).
Summary: 1) Older age, presence of neoplastic emboli and mETE were significantly more frequent in the TC-PTC and TC/CV-PTC with respect to CV-PTC; 2) After 6 yrs of follow up, BiR was more frequent in CV-PTC, while StR in TC-PTC but in particular in TC/CV-PTC.
Conclusion: The presence of tall cells, also if <50%, identifies a subgroup of PTC with an aggressive behavior and should be considered at intermediate-risk similarly to the conventional TC-PTC
18 - 21 May 2019
European Society of Endocrinology