Clinical Implications of Reticulin Fibrosis of Bone Marrow in De Novo Acute Myeloid Leukemia.

Microenvironment of bone marrow (BM) plays an important role to support proliferation, renewal and differentiation of hematopoietic stem cells. Whether the stroma of BM affects leukemic cells with the same manner, or impacts on the prognosis in leukemia patients, has not been fully investigated. Previous studies have described that increased reticulin content in the BM is associated with poor outcome in patients with acute lymphoblastic leukemia, chronic myeloid leukemia and primary myelofibrosis, but there is no cohort study to determine the clinical correlation between degree of reticulin fibrosis of BM and acute myeloid leukemia (AML). To investigate prognostic impact of reticulin fibrosis on de novo AML, 881 patients diagnosed between Jun 1999 to Dec 2011 in Chang Gung Memorial Hospital and treated with anthracycline-containing induction chemotherapy were retrospectively reviewed.

According to the grading of reticulin content in the bone marrow, we categorized the 881 patients into four groups: A. BM easily aspirated without biopsy, n = 698; B. Reticulin grade 0, n = 99; C. Reticulin grade 1–2, n = 51; D. Reticulin grade 3–4, n = 33. The induction failure (IF) rate after treatment with induction chemotherapy, the recovery duration of absolute neutrophil count (ANC) greater than 0.5 × 10⁹/L in patients who achieved the first complete remission, the overall survival (OS) and relapse-free survival (RFS) in four groups were analyzed. Based on the cytogenetic or molecular features, 648 of the patients were stratified into unfavorable, intermediate and favorable risk groups, and the clinical significance of reticulin fibrosis of BM were also examined for various risk groups.

Of the 881 patients, the patients in group D had a statistically higher IF rate (P = 0.0108) and longer ANC recovery duration (P = 0.0008). But the OS and RFS between four groups were not significantly different (P = 0.5146 and 0.3853, respectively). After risk stratified by cytogenetic and molecular analysis, increased reticulin content of BM (group C or D) had an adverse impact on OS in the intermediate and favorable risk groups (P = 0.006 and 0.0215, respectively).

Reticulin content of BM influences the IF rate and myeloid recovery for the patients of de novo AML, and affects OS in patients with intermediate or favorable risk factors.

No relevant conflicts of interest to declare.