[593] Prognostic Implications of Papillary Thyroid Carcinoma with Tall Cell Features

Ian Ganly, Tihana Ibrahimpasic, Michael Rivera, Iain Nixon, Frank Palmer, Snehal G Patel, Ashok Shaha, Robert M Tuttle, Jatin P Shah, Ronald Ghossein. Memorial Sloan-Kettering Cancer Center, New York, NY

Background: The impact of the diagnosis of a papillary thyroid carcinoma (PTC) with tall cell features (TCF) on survival is unknown.
Design: All PTC patients identified at a single institution between 1985 and 2005 were analyzed. Classical PTC (cPTC) were defined as having <30% tall cells, PTC TCF (30-49% tall cells), tall cell variant (TCV) (≥50% tall cells). All cPTC, PTC TCF and TCV ≥ 1 cm in size were included.
Results: 453 patients satisfied the inclusion criteria (288 cPTC, 31 PTC TCF and 134 TCV). cPTC patients were much younger than their PTC TCF and TCV counterparts (p<0.0002). There was an increase in tumor size from cPTC to PTC TCF and TCV (p=0.05). Extensive extra-thyroid extension was more often present in TCV and PTC TCF (55%, 52% respectively) than in cPTC (33%) (p=0.0001). Margins were more frequently positive in TCV and PTC TCF (16%,17% respectively) than in cPTC (9%) (p=0.03). Overall pathologic tumor (pT) stage was more advanced in TCV and TCV TCF (19%, 22% pT 4 respectively) than in cPTC (7% pT4) (p<0.0001). Total thyroidectomy was more often performed on TCV patients (87%) than on their PTC TCF (68%) and cPTC (70%) counterparts (p=0.014). Radioactive iodine therapy was more frequently administered to TCV (74%) than to PTC TCF (58%) and cPTC (52%) patients (p=0.0001). Median follow up was 9.3 years. 10 year disease specific survival (DSS) was lower in TCV (96%) and PTC TCF (91%) than in cPTC (100%) (p<0.001). 10 year distant recurrence free (RFS) survival was higher in cPTC (98%) than in PTC TCF (89%) and TCV (96%) (p=0.03). Within the group of patients with extensive extra-thyroid extension, TCV and PTC TCF had a poorer DSS and distant RFS than cPTC(p=0.006, p=0.04 respectively). Multivariate analysis could not be performed for DSS since only 6 patients died of disease.
Conclusions: 1) PTC TCF and TCV have the same clinico-pathologic features (e.g older age, advanced stage) that are more aggressive than cPTC 2) PTC TCF and TCV have similar DSS and distant RFS survival but poorer than classical PTC 3) PTC TCF are currently being treated like cPTC less aggressively than TCV 4) Consideration should be given to use a 30% tall cells threshold to diagnose TCV.
Category: Endocrine

Monday, March 19, 2012 1:30 PM

Platform Session: Section H, Monday Afternoon


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