Association of bone marrow fibrosis with inferior survival outcomes in chronic myelomonocytic leukemia

The impact of bone marrow fibrosis grade on the prognosis of patients with chronic myelomonocytic leukemia (CMML) remains controversial. Therefore, we examined the records of 82 patients diagnosed with CMML at our institution and summarized baseline characteristics and molecular profiles by subgroups of absent or mild (grades 0/1) and moderate (grade 2) fibrosis. Cox proportional hazards models were constructed to assess the prognostic significance of fibrosis grade. Grade 2 fibrosis was identified in 63 patients (76.8%), grade 1 in 16 patients (19.5%), and grade 0 in 3 patients (3.7%). Grade 2 fibrosis was associated with reduced hemoglobin levels (median 9.75 vs 11.0 g/dL in grade 0/1; p = 0.04) and increased percentages of ringed sideroblasts (7.5 vs 0%; p = 0.008). In multivariable analysis, grade 2 fibrosis was an independent predictor of poor overall survival (OS; 95% CI 1.32–6.35; HR 2.90; p = 0.008), but not event-free survival (EFS; 95% CI 0.62–2.67; HR 1.28; p = 0.50). Absolute neutrophil count (ANC) was found to impact OS (95% CI 1.01–1.09; HR 1.05; p = 0.009), while both ANC (95% CI 1.00–1.07; HR 1.04; p = 0.04) and peripheral blood blast percentage (95% CI 1.02–1.32; HR 1.16; p = 0.02) impacted EFS. These results implicate fibrosis grade is an important indicator of prognosis, with high-grade fibrosis predicting inferior survival. Given the prevalence of marrow fibrosis in CMML, fibrosis grading should be incorporated into prognostic assessment and therapeutic decision-making.