Minimal Disseminated Disease in Pediatric Non-Hodgkin Lymphoma

Abstract

clinical parameter such as mediastinal, visceral or skin involvement for risk stratification, the 3 yrs PFS was 58% for patients with clinical highrisk features vs 88% for standard risk patients. Thus the combination of MDD and antibody titer represents a new prognostic indicator that may be considered in the design of new ALCL trials. Lymphoblastic T-cell lymphoma (T-LBL) and T-cell lymphoblastic leukemia (T-ALL) are often considered to be part of a spectrum of a single disease. The malignant cells in T-ALL and T-LBL are morphologically indistinguishable, and immunophenotype as well as genetic abnormalities of the cells are similar. The sensitive and specific methodologies used for MRD monitoring in T-ALL, such as PCR amplification of specific genetic abnormalities and clonal IG/TCR gene rearrangement, but also flow cytometric analysis can be used to detect sub-microscopic disseminated disease also in patients with T-LBL. The very first data on the prognostic impact of minimal disease at diagnosis, evaluated by flow cytometry, was reported recently by Coustan-Smith et al. in 99 pediatric T-LBL patients [4]. Submicroscopic disease was detected in 72% of BM studied (71/99). In most of the patients a PB sample at diagnosis was also studied and every patient with detectable disease in the BM had also detectable disease in blood (r=0.86, p<0.0001). Using a cut-off level of 1%, the 2-year EFS was 68% for patients with higher levels of disease dissemination versus 91% for those with lower levels. These results indicate that flow-cytometric assay, that is at least 100-fold more sensitive than morphology, could allow a better stratification of patients for therapeutic purposes. The overall scenario indicates that similar approaches used for MRD studies in ALL may be applied to analyze MDD-MRD in NHL patients. These studies are limited in solid tumors by the different nature of the primary disease compare to ALL, which implies availability of unfixed bioptic material.