INCIDENCE, RISKS AND OUTCOME OF EXTRA MEDULLARY RELAPSE IN ACUTE LYMPHOBLASTIC LEUKEMIA IN CHILDREN AND ADULTS: A RETROSPECTIVE COHORT STUDY

Extra medullary relapse (EMR) is the major concern of treatment failure in acute lymphoblastic leukemia (ALL). Hence, their early detection may improve prognosis. Aim of the study is to identify risk factors and outcome of EMR patients with and without concurrent medullary relapse. We retrospectively analyzed 113 patients of ALL who presented with EMR in a tertiary cancer care hospital. Patients were divided into two groups; Group 1, combined EMR (with medullary relapse) and Group 2, isolated EMR (without medullary relapse). Clinical characteristics including total leukocyte count (TLC) & peripheral blood blast percentage during presentation, phenotype, initial central nervous system (CNS) involvement and BCR-ABL translocation were analyzed to identify risk factors for EMR. Incidence of EMR in our study was 15.7% (113/720 patients). Two year incidence of combined EMR and isolated EMR was 10.1% and 5.5% respectively. CNS, followed by testis was common sites of EMR. TLC >50x109/L and peripheral blood blast percentage >50% at presentation was common in Group 1. BCR-ABL translocation was frequent in Group 2 and in adults compared to children (p=0.027). While Group 1 patients presented with leukocytosis (TLC >10X109/L), Group 2 patients presented with leukopenia (TLC <4X109 p=0.001). p=0.001).>50X109/L and BCR-ABL translocation were identified as risk factors for combined EMR (p=0.004) and for in adults with isolated EMR (p=0.001) respectively.