e20672 Background: Myelophthisis is a form of bone marrow failure due to replacement of hematopoietic tissue by abnormal tissue, most commonly metastatic carcinomas. This results in extramedullary hematopoiesis, typically in the spleen leading to premature release of hematopoietic cells into the circulation. Peripheral blood findings of myelophthisis may include nucleated red blood cells, tear drop forms, giant platelets, and immature leukocytes. Overall, this picture is usually called leukoerythroblastosis. Methods: This retrospective study included 89 patients (pts) with solid tumors and myelophtisis that had been treated from 1991 to 2006 in a single reference center in Bogotá. We made a detailed analysis of pts characteristics and outcomes. Results: Mean age was 47.5±17.2 years, there was homogeneous gender distribution (F46/M43) and 62% pts had a PS ≥60%. Twenty-seven pts (30%) had breast cancer, pathology followed by primary unknown tumours (21%), rabdomiosarcoma (10%), prostate adenocarcinoma (10%), gastric carcinoma (7%) and others (22%). At the time when myelophtisis was documented 72% and 50% of pts had osseous and visceral metastasis respectively; 81 pts presented anaemia (Hb 9.8 ± 1.2 gr/dl), mean platelet count was 174,000 and mean leukocyte count was 24,283 ± 5,447. Forty-three pts received chemotherapy following the diagnosis of medullar infiltration, and normal leukocyte count was being seen in 40% of them after such treatment. Nine episodes of febrile neutropenia were found; median overall survival (OS) following the diagnosis of neoplasia and myelophtisis were 13.8 months and 2.2 months respectively. The factors related to lower survival rate were the presence of Hb ≤8.5 gr/dl (HR: 0,54, CI95% 0,32–0,95; p = 0.04), >3 metastasis sites (HR: 0,67, CI95% 0,45–0,92; p = 0.03), visceral disease (HR: 0,72, CI95% 0,66–0,89; p = 0.04) and febrile neutropenia caused by chemotherapy (HR: 0,52, CI95% 0,37–0,60; p = 0.02). Conclusions: Myelophtisis is a serious condition modifying the OS of patients having solid tumours. Treatment for this subgroup should be selected bearing in mind its potential haematological toxicity. No significant financial relationships to disclose.