Acute Myeloblastic Leukemia in Chile. Treatment and Outcomes in Patients Admitted at the Hospital Clinico De La Pontificia Universidad Catolica De Chile Between 2010–2014

Introduction: Acute Myeloblastic Leukemia (AML) is the most frequent acute leukemia in the adults and its incidence increases with age. There are few studies about the demography and outcomes of AML patients in Chile and the only report belongs to a public hospital from 2000. We discuss the results of patients treated in our institution with AML non promyelocytic.

Patients and Methods: Retrospective analysis of the epidemiologic, clinical and laboratory characteristics of diagnosis (cytology and flow cytometry) and treatment of AML non promyelocytic patients between 2010-2014. Statistical analysis of the data was performed using SPSS Statistics v21 software.

Results: 63 patients were diagnosed with AML non M3, 52 males (66%), with a median age of 55.4 years (range: 16 - 89). Diagnosis laboratory tests (mean values and ranges) were: WBC 45.989/mm3 (range: 700 - 405.000); hemoglobin 9,1 g/dl (range: 5,2 - 14,1); platelets 75.548/mm3 (range: 10.000 - 454.000); peripheral blood blasts 38% (range 0 - 100); bone marrow blasts 74% (range 25 - 100%). The cytogenetic risk groups were: favorable (n=5, 8%), intermediate (n=33, 52%), adverse (n=8, 13%) and unknown (n=17, 27%). Of all the patients, 75% (n=47) received induction chemotherapy (CT) and 25% (n=16) palliative care. The mean age of the group with cytogenetic analysis was 51.2 years and only 8.6% did not receive consolidation CT. On the other hand, the group of patients with unknown cytogenetics had a mean age of 68 years and 57% did not receive consolidation CT. The mean survival of the CT group was 27.3 month (range: 0 - 53). By contrast, the mean survival in the palliative care group was 1 month (range: 0 - 6). The mean follow up in all patients was 13 months, (range: 1 - 55) and 17 months (range: 1 - 54) in the group that received CT. 87% (n=41) of patients with CT had febrile neutropenia with respiratory and intestinal focus most commonly identified. The induction mortality was 4,2% (n=2). Complete cytologic remission was achieved in 70% (n=33). The 3-year relapse free survival (RFS) and overall survival (OS) in the CT group were 25% and 31%, respectively. The multivariate survival analysis using Cox’s regression demonstrated that the variables that had significant impact in RFS and OS were: age at diagnosis (<60 years), achievement of disease remission and the use of induction and consolidation CT (high dose cytarabine versus others). In this analysis the cytogenetic risk did not have any impact in OS. The patients that only had induction CT (but not consolidation) had significantly better survival rates compared to the group in palliative care (6 months vs. 1 month, respectively, p=0.001). The mortality during the follow up of patients who had survived the induction CT was 47% (n=22), 2/3 of leukemia and 1/3 of infections.

Conclusions: Our study shows that in our center, CR rates and OS rates after induction and consolidation chemotherapy are similar to those reported in international series, and are better than the data that was previously reported in our country. Low induction CT mortality, and the efficacy of CT in patients younger than 60 years old stand out in our report and validate the efficacy of intensive CT.