Introduction: Minimal residual disease is an important independent
prognostic factor that can identify poor responders among
patients with
acute lymphoblastic leukemia .
Objective: The aim of this study was to analyze
minimal residual disease using
immunoglobulin (Ig) and
T-cell receptor (TCR)
gene rearrangements by conventional
polymerase chain reaction followed by
homo -
heteroduplex analysis and to compare this with
real-time polymerase chain reaction at the end of the induction period in
children with
acute lymphoblastic leukemia .
Methods: Seventy-four
patients diagnosed with
acute lymphoblastic leukemia were enrolled.
Minimal residual disease was evaluated by qualitative
polymerase chain reaction in 57 and by both tests in 44. The Kaplan-Meier and multivariate Cox
methods and the log-rank test were used for
statistical analysis .
Results: Nine
patients (15.8%) were positive for
minimal residual disease by qualitative
polymerase chain reaction and 11 (25%) by
real-time polymerase chain reaction considering a cut-off point of 1 × 10−3 for precursor B-cell
acute lymphoblastic leukemia and 1 × 10−2 for
T-cell acute lymphoblastic leukemia . Using the qualitative
method , the 3.5-year
leukemia - free
survival was significantly higher in
children negative for
minimal residual disease compared to those with positive results (84.1% ± 5.6% versus 41.7% ± 17.3%, respectively; p-value = 0.004). There was no significant
association between
leukemia -free
survival and
minimal residual disease by
real-time polymerase chain reaction .
Minimal residual disease by qualitative
polymerase chain reaction was the only variable significantly correlated to
leukemia -free
survival .
Conclusion: Given the difficulties in the implementation of
minimal residual disease monitoring by
real-time polymerase chain reaction in most
treatment centers in
Brazil , the qualitative
polymerase chain reaction strategy may be a
cost -effective alternative.