Bone marrow microvessel density and its prognostic significance in AML.

Microvessel density reportedly is increased in various hematologic disorders including acute lymphatic and myeloid leukemias. In these patients the bone marrow microvessel density (BM-MVD) appears to be associated with an unfavorable prognosis. In the present study, we have retrospectively analyzed the BM-MVD (at diagnosis) in 31 patients with acute myeloid leukemia (AML) (median age: 38 years; range: 21-53 years; f:m-ratio: 1:1,4) who underwent conventional chemotherapy and consecutive allogeneic bone marrow transplantation (BMT). The median BM-MVD at diagnosis was 30/mm2 (range: 17-48/mm2) and thus was significantly higher compared to controls (n = 9; BM-MVD: median 7/mm2, range 2-11/mm2; P < 0.05). In patients who failed to achieve a complete remission (CR) in response to induction chemotherapy, the BM-MVD was significantly higher (median: 41.5/mm2) at diagnosis than in patients who entered CR (median: 28.5/mm2, P < 0.05). In addition, patients with high BM-MVD ( > 30 mm2) had a significantly shorter overall survival compared to patients with a lower BM-MVD ( < 30 mm2, P < 0.05). Moreover, patients with a high BM-MVD ( > 30 mm2) were found to have a significantly higher risk of relapse (P < 0.05). In 4 patients in whom a continuous complete remission was documented after BMT, the BM-MVD levels were analyzed at diagnosis as well as between day + 80 and day + 100 after BMT. In all 4 patients, the BM-MVD was found to decrease in response to BMT until day 100 (P < 0.05). Together, our data suggest that the BM-MVD could be a prognostic parameter concerning survival in patients with AML undergoing allogeneic BMT.