Cause-Specific Mortality and Prognostic Impact of Comorbidity in Japanese Patients With Chronic Lymphocytic Leukemia

Background: Due to its rarity, there are very limited data available on the cause of death (COD) and its association with comorbidities in Japanese chronic lymphocytic leukemia (CLL) patients. Methods: To investigate the prevalence of comorbidities and their impact on cause-specific mortality, we retrospectively reviewed 121 Japanese patients with CLL. Results: The median age was 69 years, with 47.9% having at least one comorbidity listed in the Charlson Comorbidity Index (CCI), and 12.4% were multimorbid. With a median follow-up of 74 months, the 5- and 10-year overall survival rates were 80.6% and 60.1%, respectively. Among the 44 deaths observed, CLL progression was the leading COD (38.6%), which together with infections and other malignancies accounted for nearly 80%. Patients with higher CCI risk categories had significantly higher 5-year all-cause mortality (CCI 1-2: 22.9% and >= 3: 31.4%) and non-CLL-specific mortality (CCI 1-2: 18.8% and >= 3: 31.4%) compared to those without (CCI 0: 12.6%, p = 0.005; 3.5%, p < 0.001, respectively), whereas CLL-specific mortality was not influenced. On multivariate analysis, age and CCI retained a significant prognostic impact on all-cause mortality (hazard ratio [HR] 1.08, p < 0.001 and HR 1.88, p = 0.004, respectively) and non-CLL-specific mortality (HR 1.12, p < 0.001 and HR 3.81, p < 0.001, respectively). Conclusions: Our study showed that CLL itself was the leading COD, and comorbidity burden was associated with non-CLL-specific deaths. This highlights the importance of better disease control and effective management of comorbidities.