Bone marrow fibrosis impact on response to azacitidine in myelodysplastic syndromes.

Bone marrow fibrosis in myelodysplastic syndromes (MDS) has been associated with poor outcome. However, these studies were conducted prior to the widespread use of azacitidine in the management of MDS. Our study aimed to assess whether treatment with azacitidine ameliorates the inferior outcome in MDS with fibrosis. A retrospective study of all patients diagnosed with MDS and treated with azacitidine over 3 years in two institutions was performed. A total of 21 patients were included in this study. Approximately half of these had moderate to severe bone marrow fibrosis at the start of treatment with azacitidine. The median overall survival was 34 months in patients with non-fibrotic bone marrow compared to 14 months in patients with fibrotic marrow (p=0.0007). Median event-free survival was 26 months versus 12 months (p=0.0027) in patients with non-fibrotic and fibrotic marrow, respectively. In multivariate analysis, bone marrow fibrosis was an independent factor in overall survival. Transfusion requirement was not different between the two groups. Despite the small sample size, we observed a worse outcome in azacitidine treated patients with MDS and fibrotic marrow. We suggest a prospective larger study to confirm the above finding.