Sézary Syndrome: Survival Trends, Racial Disparities, and Limited Prognostic Value of Routine Registry Variables

ABSTRACT Introduction Sézary syndrome (SS) is a rare leukemic cutaneous T‐cell lymphoma with limited contemporary population‐level outcome data. Methods Using SEER‐22, we identified 403 adults with first primary SS diagnosed from 2000–2021 and evaluated survival, disparities, and prognostic modeling. Results Median overall survival (OS) was 48 months; 5‐year OS was 42.7%. Survival improved from 39.5 months in 2000–2010 to 56.0 months in 2011–2021. Black patients were diagnosed younger and had worse adjusted mortality than White patients. Machine‐learning and conventional models showed limited discrimination. Conclusion SS remains highly lethal, with persistent racial disparities and limited prognostic value of routine registry variables. Trial Registration The authors have confirmed clinical trial registration is not needed for this submission