Time trend in frequency of occurrence of major immunophenotypes in paediatric acute lymphoblastic leukemia cases as experienced by Cancer Institute, Chennai, south India during the period 1989-2009

Pediatric acute lymphoblastic leukemia (ALL) is a biologically heterogeneous disease and socioeconomic and environmental factors are considered to be an important determinant of its immunophenotype. The aim of this analysis is to study the time trend in the immunophenotype of pediatric acute lymphoblastic leukemia (ALL) cases in our geographic setting. A total of 639 new pediatric ALL cases immunophenotyped during 1989-2009 forms the basis of this analysis. Representative bone marrow or peripheral blood of these patients was immunophenotyped flowcytometrically using an extensive panel of monoclonal antibodies. During early phase of our study we noticed a relative excess of T-ALL and a paucity of common acute lymphoblastic leukemia (C-ALL) in contrast to western data. Over a period of 20 years we witnessed a gradual reduction in pediatric T-ALL cases and a proportionate increase in C-ALL cases. We find that this change of pattern is synchronizing with the socioeconomic and industrial development prevailing in our geographic setting and suggest a possible link between the predominant immunophenotype of pediatric ALL cases and the environmental and socioeconomic factors prevailing in that locality.