Incidence, Clinical Features, and Outcomes of Large Granular Lymphocyte Leukemia

Introduction: -

Large Granular Lymphocyte (LGL) leukemia is a rare and diverse hematologic disorder characterized by the clonal proliferation of large granular lymphocytes in the peripheral blood and bone marrow. Despite its rarity, population-based studies on LGL leukemia remain limited. This study aims to comprehensively analyze clinical characteristics and outcomes among patients with LGL leukemia.

Methods: -

We utilized the Surveillance, Epidemiology, and End Results (SEER) database 17 registry to identify patients diagnosed with large granular lymphocytic leukemia between 2000-2020. Data analysis was conducted using SEER*Stat version 8.4.1.2 and STATA. Univariate survival analysis was done using a Kaplan Meir plot with a log-rank test, and the Cox proportion hazard regression model was used for multivariate survival analysis.

Results: -

We identified a total of 2,589 LGL leukemia cases during the study period. The calculated incidence of LGL leukemia was 0.14 cases per 1,000,000 individuals (range: 0.14 – 0.15). Male patients exhibited a higher incidence rate ratio of 1.19 (95% CI: 1.11 – 1.27, p < 0.01) than females. However, females tended to be diagnosed younger than males (67 vs. 68, p < 0.01). Most cases were observed in the White population (83%) compared to other racial groups. The median age at diagnosis was 67 years (ranging from 7 to 85 years). Patients aged above 70 years showed the highest incidence of LGL leukemia (0.80) in contrast to those aged 45-54 years (0.30) and 55-64 years (0.63). Notably, there was a significant increasing trend in LGL leukemia incidence, with an incidence rate ratio of 13.50 (95% CI: 10.5–17.6, p < 0.001) in the period 2015–2019 compared to 2000–2004.

Approximately 32.7% of patients received chemotherapy; the median time from diagnosis to treatment was one month. The survival rates at 12, 36, and 60 months for LGL leukemia patients were 88.9%, 76.5%, and 66.5%, respectively, with a median follow-up of 40 months. Multivariate analysis revealed that females had a more favorable survival outcome than males (HR: 0.78, 95% CI: - 0.64 – 0.97, p: 0.02). Moreover, patients who underwent chemotherapy exhibited better survival than those who did not (HR: 0.72, 95% CI: 0.56 – 0.93, p: 0.01). Elderly patients above 60 years of age had poorer survival rates (HR: 3.1, 95% CI: 2.34 – 4.01, p < 0.01), and no significant difference in outcomes was observed based on the timing of chemotherapy initiation from the time of diagnosis.

Conclusion: -

This study represents the most extensive and most recent population-based investigation of LGL leukemia. The findings highlight the potential benefits of chemotherapy in improving survival and indicate better outcomes in female patients. Further research is warranted to validate these promising results and gain deeper insights into the management and prognosis of LGL leukemia.