Epidemiological Approach of Chronic Myeloid Leukemia. Algerian-Tunisian Study

Introduction: Chronic myeloid leukemia (CML) accounts for 7%-15% of all leukemias affecting adults. The incidence in Algeria is 0.4/100,000 inhabitants in 2009. The aim of this study is to establish an Algerian-Tunisian epidemiological approach of CML and to know the characteristics of the disease in both countries.

Materials and methods: This is a retrospective, longitudinal and multicenter study, including Algerian and Tunisian patients with CML diagnosed between January 2010 and December 2014. Through a data form distributed to various hematology departments, we collected and analyzed the following information: Patient's general characteristics, profession, circumstances of discovery of the disease, clinical and para-clinical examinations outcomes at the time of diagnosis including blood count, blood smear, bone marrow aspiration, cytogenetics, molecular biology, stages of the disease and the Sokal and Eutos prognostic classification scores. Bio-statistical tests: incidence, prevalence and rate of prevalence or relative prevalence (reported to 100,000 inhabitants / year). The descriptive analysis of quantitative and qualitative variables as percentages and 95% confidence interval. The Chi2 test is used to compare two variables.

Results: We collected 1349 cases, including 325 from 06 Tunisian hematology units and 1024 from 18 Algerian units. The incidence in the Algerian-Tunisian population was 0.67/100,000 inhabitants with a prevalence rate of 2.72/100,000 inhabitants. The incidence in Tunisia was 0.50 / 100,000 inhabitants with a prevalence of 227 cases in 2014. In Algeria the incidence was 0.53/100,000 inhabitants with a prevalence of 1030 in 2014. The median age is 48 years (03-90) with a peak incidence in the age group (45-49 ans) and slight male predominance (sex ratio: 1,2). There was any notion of risk exposure. The average time between the start of the unrest and the date of diagnosis is 127 days (1-667). The circumstances of discovery: fortuitous in 30.5% (n = 355), splenomegaly in 39.7% (n = 463), asthenia in 24.6% (n = 287), a complication in 8.4% (n =95). Clinical examination includes general signs in 424 cases (36.4%): Weight loss 22.6% (n = 263), profuse sweating 13.8% (n = 13, 8%), bone pains found in 7.8%, splenomegaly in 81.7% (n = 952) with an overhang splenic average of 11.5 ± 5.3 cm (1-28), cutaneous and subcutaneous bleeding: 13.5% (n = 97), thrombosis 0.9% (n = 09). Biological characteristics: the Complete blood count (n = 1185) shows a white blood cells average rate of 171,223 G/L (34,700-984,800), hemoglobin average rate of 10.2 g/dl (4-17), platelets at 394,070 g/l (85-1340). Blood smear 96.3% (n = 1121): the average myelemia was 43.2% (10-98%). The Myelogram is practiced in 55% (n = 641), the average rate of the granular 76,5% (40-99%), erythroblasts 10.5% (0-82%), average blasts 3.6%. The karyotype 38.1% (n = 444), the Philadelphia chromosome was found in 423 cases (95, 3%); additional abnormalities were found in 17 cases (3.8%). The Fish was practiced in 281 cases (24.1%) and transcribed bcr/abl was found in 257 cases (91.4%). Molecular biology is practiced in 672 cases (57.7%) the transcript bcr/abl is found in 100%, the transcript of the type is specified in 373 cases, it is kind of b2a2 in 159 cases (42.6%), a b3a2 type in 180 cases (48.3%) and other transcribed in 34 cases (9.1%). CML chronic phase is diagnosed in 88.8% (n = 1051), acceleration phase in 9% (n = 107) acutisation phase in 3.1% (= 37). The distribution of pts according to Sokal prognostic classification (n = 948) describes a predominance of intermediate risk in 54% (n = 511), high risk in 30.3% (n = 287) and low risk in 16% (n = 152). The Eutos score is specified in 769 cases (66%), it is less than 87 in 661 cases (86%) and more than 87 in 108 cases (14%).

Conclusion: The incidence of CML in the Algerian-Tunisian population is 0.67/100,000 population with a prevalence rate of 2.72/100,000 inhabitants. The young adult is more affected with a peak incidence between 45 and 49. The average time between the onset of the disease and the diagnosis remains long and the delay probably explains the frequency of tumor forms encountered in Algeria and the prevalence of high and intermediate risk, according to Sokal prognostic classification.