8760 Does an Increased Size of Thyroid Nodules Correlate with a Higher Probability of Intermediate or High-Risk Histopathological Features for Recurrence?

Abstract Disclosure: R. Pishdad: None. N. Yousefzadeh: None. E. Gough: None. L. Rooper: None. J.S. Mammen: None. Does an increased size of thyroid nodules correlate with a higher probability of intermediate or high-risk histopathological features for recurrence? Background: The existing practice guidelines recommend total thyroidectomy for solitary nodules exceeding 4 cm regardless of other pre-operative findings. We hypothesize that through comprehensive pre-operative assessments, particularly including a thorough neck ultrasound, even nodules exceeding 4 cm that would otherwise meet ATA criteria for lobectomy (i.e., lacking extrathyroidal extension and suspicious lymphadenopathy) will not exhibit occult high-risk features at a higher rate compared to nodules measuring 1-4 cm. Consequently, these larger nodules would not necessitate a higher rate of completion thyroidectomy. Methods: Solitary thyroid nodules with a largest dimension ≥ 1 cm and operated on at a single institution between 2005 to 2023 were assessed to identify those that would have met ATA criteria for lobectomy. Surgical pathology reports were reviewed to perform risk stratification following ATA guidelines. Preoperative cytopathology, ultrasound characteristics, and patient demographics were considered as covariables. Statistical analyses were performed with R programming language. Simple logistic regression and multivariable logistic regression were performed to analyze the finding of occult intermediate or high-risk features based on size. Results: We identified 461 cases of solitary nodules without extrathyroidal extension or lymph node involvement (406 nodules 1-4 cm; 60 nodules ≥ 4 cm). Patients with larger nodules were more likely to be male than those with smaller nodules (52% versus 26%; P value <0.001). Interestingly, while the majority of smaller nodules meeting criteria for lobectomy were suspicious or malignant by cytopathology (Bethesda 5 and 6), only 20% of larger nodules that met criteria were malignant, with 68% either Bethesda 3 or 4 (p<0.001). There were no statistically significant associations between size or other variables such as age, race, sex, or positive family history and post-operatively assessed high/intermediate risk for recurrence. Conclusion: In this analysis of solitary nodules with larger sizes, the dimension itself did not emerge as a risk factor for occult intermediate or high-risk surgical pathology. Thus, the rates of completion thyroidectomy in appropriately screened patients would be acceptable even in patients with nodules greater than 4 cm. The majority of larger nodules that fulfill preoperative ATA criteria for lobectomy were assessed to be ACUS or a follicular neoplasm on pre-operative fine-needle aspiration. This suggests that the higher risk of more aggressive disease previously reported with larger nodules can be detected during preoperative assessment, emphasizing the essential role of neck US in the comprehensive evaluation of larger nodules. Presentation: 6/2/2024