Epidemiological, Clinical, and Biological Characterization of Newly Diagnosed Acute Myeloid Leukemia in Algeria. Report on Behalf of the Algerian Acute Leukemia Study Group

Introduction:

Acute myeloid leukaemia (AML) is a group of heterogeneous malignant disorders. AML incidence rates in world populations generally ranged from 3.0 to 4.0 cases per 100,000 person-years in adult populations, while developing countries had about one-third the incidence of AML. In Algeria there are no large-scale studies regarding acute myeloid leukemia epidemiology. The objective of this study was to analyze the initial basic characteristics of patients diagnosed with AML in our population and the incidence rate.

Patients and methods:

A survey form was distributed to all departments of hematology at the 21 participating centers of the Algerian AML Study Group (A.AMLSG). In this multicenter, retrospective study, 2,231 patients were included between 2011 and 2017. We intended to register all patients aged 15 years or older with newly diagnosed AML. Data noted age at presentation, gender, medical history, physical examination, and blood and bone marrow investigations such as, hemoglobin levels, blood cell count, and AML subtype according to flow cytometry analysis. AML cases were classified according to the 2008 World Health Organization (WHO) proposal. Age-standardized incidence rates (ASR) of AML were calculated using Algerian population data in the years 2011-2017. SPSS 20 was used for data analysis.

Results:

Of the 2,231 patients, 1059 (47%) were females and 1172 (53%) males, with a mean of 318.7 cases per year for the whole country. The overall mean age was 46.7±18.2 years. The most common age group was 30-70 years with 1444 (64.7%) patients. Most frequent clinical features at presentation included fever 987/2120 (46.5%), weakness 532/2120 (25%) and bleeding tendency 1033/2120 (48.7%). A significant number of patients had presented with body aches, respiratory complaints and hepatosplenomegaly or other abdominal complaints. Median hemoglobin levels was 7.6 g/dl (IQR: 2.4 - 14,8), whereas median counts for white blood cells (WBC), platelets and blasts were 20 G/L (IQR: 0,2-260), 35,5 G/L (IQR: 1-425) and 58% (IQR: 28-100), respectively. AML subtypes were available for 1946 (87.2%) patients. The most common AML subtype according to latest WHO classification was "AML with maturation" (M2) having 499 (26%) patients, followed by acute monocytic leukemia (M4) with 378 (19.4%). APL was the fourth most frequent pathology with 283 (15%) cases, 147 (52%) were females and 136 (48%) males, with a mean age of 37±16,1years. According to the SANZ classification, patients were diagnosed with favorable risk (N = 31, 11%), intermediate risk (N = 107, 38%), and adverse risk (N = 145, 51%). Cytogenetic studies were performed in 21% of the patients, and molecular biology studies were performed in 12% of the patients. Mutated FLT3-ITD was present in 12 patients (16%) among 75 patients. The trend of continuous annual increase in cases of AML where 250 cases had been registered in 2011, 252 in 2012, 339 in 2013, 290 in 2014, 320 in 2015, 370 in 2016 and 410 in 2017. According to their place of care, the patient distribution shows that over 58% had been diagnosed in the seven oldest hematological centers in the country, while according to their place of residence, the city of Algiers had the highest frequency of 12.9%. Globally, 28% of AML were diagnosed in the whole western region of the country, 43% in the center and 29% in the east. The crude annual incidence per 100 000 of the population continued to rise from 0.94 in 2011 to 1.39 in 2017. The age-specific incidence varied from 0.72 for ages 15- 20 years, with a trend of a continuous increase in the rate, and a sharp increase to 2.44 after age 60 years reaching the highest 2.63 after age 80.

Conclusion:

The young population in Algeria was expected to result in a relatively lower AML incidence rate and median age since AML incidence usually occurs much later in life. An overall increase in the number of AML patients diagnosed nationwide over the last seven years indicates a need for additional health care resources including curative and therapy-intense strategies, such as stem cell transplant facilities to optimize outcome.