Minimal residual disease is the most powerful predictor of outcome in acute
leukemia and is useful in
therapeutic stratifi
cation for
acute lymphoblastic leukemia protocols. Nowadays, the most reliable
methods for studying
minimal residual disease in
acute lymphoblastic leukemia are multiparametric flow cytometry and
polymerase chain reaction. Both provide
similar results at a
minimal residual disease level of 0.01% of normal
cells, that is,
detection of one leukemic
cell in up to 10,000 normal nucleated
cells. Currently,
therapeutic protocols establish the
minimal residual disease threshold value at the most informative
time points according to the appropriate
methodology employed. The expertise of the
laboratory in a
cancer center or a cooperative group could be the most important factor in determining which
method should be used. In
Brazil, multiparametric flow cytometry
laboratories are available in most
leukemia treatment centers, but multiparametric flow cytometry processes must be standardized for
minimal residual disease investigations in order to offer reliable and reproducible results that ensure quality in the clinical application of the
method. The
Minimal Residual Disease Working Group of the Brazilian Society of
Bone Marrow Transplantation (SBTMO) was created with that aim. This
paper presents recommendations for the
detection of
minimal residual disease in
acute lymphoblastic leukemia based on the
literature and expertise of the
laboratories who participated in this
consensus, including pre-analytical and
analytical methods. This
paper also recommends that both multiparametric flow cytometry and
polymerase chain reaction are complementary
methods, and so more
laboratories with expertise in
immunoglobulin/
T cell receptor (Ig/TCR)
gene assays are necessary in
Brazil.