Abstract 6262: Optimal cut-off age for AJCC staging system in Middle Eastern patients with differentiated thyroid cancer

Abstract Background: Differentiated Thyroid Cancer (DTC) has an indolent nature and generally has favorable prognosis. AJCC TNM classification is the most adopted system to evaluate the biological behavior of DTC. Age cut-off of 55 years has been included in the eighth edition of TNM staging system since it led to better prediction of disease specific survival (DSS) of patients with DTC. However, optimal age cut-off in DTC patients from Middle Eastern ethnicity has not been fully explored. We evaluated the optimal age cut-off for the TNM staging system to predict DSS in Middle Eastern patients with DTC. Methods: We retrospectively analyzed a large cohort of 1721 adult DTC patients who underwent surgery between 1990 to 2018. The optimal age cut-off value was determined using several age cut-offs (between 20 and 85 years) to assess DSS. Harrel’s C-Index, Akaike information criterion (AIC) and Bayesian Information Criterion (BIC) were used to assess the statistical model performance of the TNM staging system (eighth edition), with different age cut-offs for prediction of DSS. The proportion of variation explained (PVE) was also calculated to compare predictability of DSS in patients with DTC. Results: The median age of patients at diagnosis was 39.9 years (IQR 31.0 - 51.7 years) and 75.5% (1299/1721) were female. Median follow up was 9.3 years and 10 years DSS was 97.1%. For DTC overall, an age cut-off of 50 years had the best statistical model performance. On receiver operating characteristic curve analysis, the optimal age cut-off for prediction of DSS was 50.5 years (area under the curve = 0.872, p < 0.0001). Conclusion: In this large cohort of Middle Eastern DTC patients, an age cut-off of 50 years was more appropriate for TNM staging to achieve better predictability for DSS. Therefore, implementation of different age cut-off for DTC in Middle Eastern patients could improve the predictive value for TNM staging system, and allow for better therapeutic and surveillance approach for these patients. Citation Format: Sandeep K. Parvathareddy, Abdul K. Siraj, Padmanaban Annaiyappanaidu, Saeeda O. Ahmed, Nabil Siraj, Zeeshan Qadri, Saud Azam, Khawla S. Al-Kuraya. Optimal cut-off age for AJCC staging system in Middle Eastern patients with differentiated thyroid cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6262.