Prognosis and Survival of Acute Myeloid Leukemia: Experience of a Single Center in Colombia

Background: Acute Myeloid Leukemia (AML) is the most common acute leukemia in adults in the United States with an incidence of 3 to 5 cases per 100,000 population [Siegel RL, CA Cancer J Clin 2018)]. Even though advances in therapies have increased the survival and improved outcomes in younger population, patients over 65 years of age carry a particularly poor prognosis. Previous results of treatment outcomes in AML have showed significant differences between low- and middle-income countries (LMIC) and high-income countries (HIC). The aim of this study is to assess survival rate for patients with diagnosis of AML in a single center in Colombia, South America.

Methods: A retrospective cohort study was conducted at a tertiary referral center in Colombia on patients older than 15 years who were diagnosed with AML between July 2013 and November 2017. All patients were managed based on PETHEMA protocol for AML. Descriptive statistics were used to analyze patient's demographic characteristics. The Kaplan-Meier method was used to assess overall survival (OS) and relapse-free survival (RFS) rates at one and five years.

Results: One hundred and seventeen patients were included. Fifty-nine were male (50.42%) and 58 were female (47.6%) with a mean age of 63 years (range 15-95). The most common type of AML based on the French-American-British (FAB) classification was M2 (AML with maturation) in 22.8% of the patients, followed by M1 (AML with no maturation) in 10.5%, and M5 (acute monoblastic leukemia with or without maturation) in 8.8% of the patients; however, classification data was missing in several of the patients (45.6%).

OS was 54.6% (CI95% 44.4-63.7) at one year and 19.5% (CI95% 10.3-30.9) at five years. RFS was 91.4% (CI95% 84.0-95.4) at one year and 83.3% (CI95% 73.9-89.5) at five years. Classifying patients by age group, OS was 81.8% (CI95% 68.7-89.7) at one year and 36.5% (CI95%19.6-53.6) at five years for patients younger than 65 years, 22.8% (CI95% 10.8-37.5) at one year and 0% at five years for those between 60 and 80 years, and 19.1% (CI95% 1.4-52.4) at one year and 0% at five years for patients older than 80 years. While median OS for patients who achieved complete response after induction regimen was 35.7 months, it was only 8.9 months for those with either partial response or induction failure (HR 1.03, CI95% 1.01-1.05, P<0.01). Median OS by type of treatment was 32 months for idarubicin + cytarabine (3+7), 7 months for FLUGA - fludarabine + cytarabine, and 1 month for those who only received supportive therapy. Only four patients, all older than 60 years, received treatment with hypomethylating agents, none of them achieving any response. The most common cause of death was disease progression (26%), followed by infection (22%).

Conclusions: Patients with diagnosis of AML receiving standard combination chemotherapy with idarubicin and cytarabine had better survival rates than patients receiving semi-intensive chemotherapy schemes. The most common cause of death in AML patients was primary disease, and treatment-related mortality was low.