Epidemiology and Clinical Features of Chronic Lymphoid Leukemia. Review of the Algerian Chronic Lymphoid Leukemia Study Group

Introduction: Chronic lymphocytic leukemia (CLL) is the most frequent leukemia of the adult in Europe and North Africa. It is rare on the Asian and African continents. It affects mainly elderly people over 60 years. The main objective is determining the rate of average annual incidence, and secondly establishing the distribution of this complaint according to the different health regions of the country and precise the epidemiological characteristics.

Patients and Methods: It is a national, descriptive, retrospective epidemiological study carried out for a period of 05 years : from January 2009 to December 2013. Information collection is done thanks to the setting up of a technical data sheet sent out to the appropriate services. This technical data sheet is about the geographic data of the patient (place of birth, place of residence, place of taking charge of the disease and the date of the diagnosis), anthropologic data (age at the diagnosis, sex), as well as the clinico-biological data. The working of the responses was done on SPSS 19 .0. In our study, the diagnosis is carried before an hyperlymphocytosis > 5000/ mm³, a cytological examination of the blood smear and an immunophenotyping operation by cytometer operation in flow.

Results: 17 hematology departments have participated in this study with 1210 cases listed, of which 68,1% (824 pts) are men. The average annual recruitment is of 242 cases. The average annual incidence rate, calculated according to the data of the national statistics office is estimated at 0,66 / 100.000 inhabitants.This incidence does not increase over the years and stays relatively stable (2009 = 0,67; 2010 = 0,57; 2011 = 0,63; 2012 = 0,67; 2013 = 0,74/100.000 inhts). The geographic distribution of the pts according to their places of residence, shows that the majority among them are from the north of the country particularly the center (0,80/100.000 inhts). Incidence increases over age, going among men from 0,06 for 100.000 inhts between 30 - 39 years to 11,94 / 100.000 inhts at 80 years and over and among women from 0,04 for 100.000 inhts to 6,08 for 100.000 inhts. The average incidence rate is of 0,85/100.000 inhts among men and of 0,42/100.000 inhts among women. The average age at the diagnosis is of 67,5 years (33 - 98 years). 30,1% (365 pts) incident cases are observed among the patients over 75 years and 14,1% (171 pts) among the patients below the age of 55 years. The profession that is most found is farming 12.2% (78/635 precised). The diagnosis is late in Algeria, the first symptome which brings the patient to consultation is the tumoral syndrome (44% (363 / 825 precised)) in an average diagnosis period of time of 07 months (01 - 96 months). The stage C (classification of Binet) is equally predominant, found in 41,1% (492 / 1172 precised). In terms of biology : the average rate of lymphocytes is of 92500/mm3 (5000-900 000/mm³). The morphological study on blood smear finds 88,2% (1066 / 1208 precised) of typical CLL and 50% of Gambrest cells. The cytometer operation in flow done in 746 cases (61,6%) shows a score of matutes > 4 in 92,3% and in 7,7% is equal to 3. the cytogenetic operation (Caryotype and Fish) done in only one hematology department (CAC of Blida) among 102 patients (8.4%).

Comments: The rate of incidence in Algeria is weak compared to that of other countries. The rate of incidence standardized to the world population is of 0,52 cases/100.000 inhts and to the European population is of 0,68 cases p 100.000 inhts. The young age of the population may explain this incidence and that some patients at the stage A are not diagnosed. The CLL affects more frequently men. The average age at the diagnosis is of 67,5 year. However, 30,1% of the incident cases are observed among the patients over 75 years in Algeria versus 45 à 50% of incident cases in Europe and this may be explained by the young age of our population. The CLL are placed 5th among the malignant hemopathies: the rate of incidence for the year 2009 : LNH = 1.96; LH = 1.2; MM = 0.96; AML = 0.85; CLL = 0.67; CML = 0.44; ALL = 0.32.

Conclusion: the CLL can be diagnosed and differentiated from the other lymphoproliferative syndromes thanks to the morphological examination of the lymphocytes at the blood smear completed by an immunophenotyping operation of the peripheral blood . This study represents only an epidemiological approach of the CLL in Algeria. The incidence is still weak in our country; it affects as in the other countries the elderly people with a masculin predominance.