Minimal residual disease by flow cytometry at the end of chemotherapy for remission induction in pediatric patients with acute lymphoblastic leukemia: Experience from a center in a low-income country.

9554 Background: The presence of minimal residual disease (MDR) following therapy for acute lymphoblastic leukemia (ALL) has been shown to be an important prognostic marker in many studies. MRD is typically detected either by polymerase chain reaction amplification or by flow cytometry. Flow-based MRD assessment has the potential for rapidly identifying patients at increased risk of relapsed, allowing for prompt changes in therapy, including earlier intensification. There are not many information about the response by MRD in countries with limited resources. Methods: The patients included were 90 ALL patients treated at the Hospital Infantil de Morelia from June 1, 2009 to January 5, 2012. MRD positivity (+) was defined as >0.01% of the gated population. Results: MRD was obtained in 90 patients, 38 males and 36 females. The median age was 7 years (10 months to 15 years). The levels of MRD were: <0.01, 74 (82.2%), 0.01-1%, 9 (10%), ≥1%, 7 (7.7%). There was not a statistically significant association between the most important ALL prognostic factors (Gender, Age at diagnosis, White blood cell count at diagnosis, Central Nervous System disease, Prednisone response, DNA Index, Immunophenotype). Conclusions: The good response found is similar to that reported by international groups, a situation which suggests that the response to chemotherapy is appropriate. However, cure rates are still not equal making it necessary to review institutional treatment protocols and social characteristics of the population to achieve cure rates reported by international groups.