Life Expectancy of Hairy Cell Leukemia Patients Approaches General Population: Insights from a SEER Study of 5669 Cases

Introduction: Hairy cell leukemia (HCL) is a rare lymphoproliferative disorder affecting mature B-cells, predominantly observed in males. It is recognized by cytopenia, splenomegaly, myelofibrosis, and the presence of atypical lymphoid cells exhibiting distinctive cytoplasmic hairy projections. Methods: This is a population-based study that utilized updated HCL clinical data from the Surveillance, Epidemiology, and End Results (SEER) database, this study identified HCL patients diagnosed between 1978 and 2020. A total of 5669 patients were included after data screening by inclusion and exclusion criteria. Univariate and multivariate COX regression models were used to study the factors that affect the overall survival (OS). Result: Estimated median survival for HCL patients who aged less than 40 years was 39.3 (95% CI: 38.9-39.7 years) compared to 8.8 years (95% CI: 8.0-9.4 years) for HCL patients older than 65 years, which closely approaching life expectancy of general population. Also, patients diagnosed by multiple advanced methods like immunophenotyping and genetic studies exhibited a reduced Hazard ratio (HR) = 0.52 (95% CI: 0.38-0.72) compared to using histology alone. Conclusion: This study found that the life expectancy of HCL patients is very close to that of the general population. Improved OS is associated with recent diagnoses (post-2006), chemotherapy treatment, and usage of multiple advanced diagnostic methods, such as immunophenotyping and genetic studies.