12210 Prognostic Determinants of Aggressive Histology Papillary Thyroid Carcinoma: A Pathway to Personalized Treatment

Abstract Disclosure: M. Almaghrabi: None. G. Sindi: None. H. Sasseville: None. S. Radi: None. M. Tamilia: None. Background: Papillary thyroid carcinoma (PTC), the most common form of thyroid malignancy, generally presents with a favorable prognosis. However, aggressive variants of Papillary Thyroid Carcinoma (AV-PTC), such as tall cell, hobnail, columnar, and solid forms, pose significant challenges in prognosis and treatment, due to their unique pathological behaviors and increased risks of recurrence and mortality. The management debate for AV-PTC without invasive characteristics is ongoing. It's argued that aggressive histology alone should not dictate the clinical management of PTC patients lacking aggressive features. Objectives: This study aims to investigate the prognostic impact of invasive features in AV-PTC and their implications on clinical outcomes. Methods: We conducted a retrospective cohort study of AV-PTC patients treated from 2008 to 2022, analyzing medical records to identify prognostic factors related to disease recurrence, persistence, and overall survival. This involved distinguishing between groups with invasive characteristics—identified as one of the following: extrathyroidal extension, lymphovascular invasion, the presence of positive lymph nodes, or the detection of distant metastases upon diagnosis, and non-invasive AV-PTC groups. Results: Key findings from our comparison between invasive and non-invasive groups of AV-PTC highlighted significant factors associated with poorer outcomes in the invasive group. These included multifocality (P=0.001), larger tumor size (P=0.047), extra thyroid extension (P=0.002), lymph vascular invasion (P<0.001), the presence of contralateral nodules (P=0.018), and positive surgical margins (P=0.003). Moreover, advanced tumor stage and increased lymph node involvement were more common in invasive cases (P=0.012, P=0.040). Despite no significant differences in genetic mutations between groups (P=0.396), the Ki-67 index was numerically higher in the invasive group. Hemithyroidectomy followed by completion thyroidectomy, performed in 12 patients (22.2%). Survival analysis further highlighted the significance of these invasive features, with Kaplan-Meier curves indicating a 5-year freedom from recurrence rate of 77.18% and a 10-year rate of 68.61%. Univariable Cox regression revealed that the tumor size, positive margins, and tumor stage predicted recurrence. Seven patients had distant metastasis, and all were in the invasion group (18.92%) p= 0.088. Conclusion: Our study emphasizes the critical role of certain invasive features in determining the prognosis of AV-PTC. The adoption of more extensive treatments for patients without invasive features highlights the complexity of treating AV-PTC and the importance of personalized treatment plans. This research advances our understanding of AV-PTC, advocating for individualized approaches to enhance patient outcomes. Presentation: 6/3/2024