Degree of Concordance between Peripheral Blood Leukemic Blast Count and Mid Induction Bone Marrow in Childhood Acute Lymphoblastic Leukemia.
Abstract While different Pediatric ALL study groups have used varying definitions of early response (BM vs. PB, prophase vs. day 7 vs. day 14), all agree that it provides critical prognostic information. Bone Marrow aspiration and biopsy (BMA/B) is an invasive procedure requiring sedation or anesthesia, and an early/mid induction specimen may be difficult to interpret even by experienced hematopathologists. In this study we attempted to determine if there was a concordance between peripheral blood blast (PBB) clearance and the findings of the day 14 BMA/B, and whether day 7 PBB count could reliably replace a mid induction BMA/B. Clinical data for newly diagnosed pediatric (<14 years) ALL patients between January 1999 and December 2001 were retrieved from our prospective database. Day 14 BMA/B slides were reviewed independently by two hematopathologist. For the total 165 patients, median age was 4 years, 53.9% were boys. Complete information was available for 151 of these patients and further analysis is based on this number. 124 (82.1%) were treated with 4 agents while the remainder received a 3-drug induction. 23 (18.5%) had positive PBB on D7, and 21 (13.9%) had >5% blasts in the D14 BMA/B. The D7 PBB count could positively and negatively predict the D14 BMA/B 71.9% and 89.4% of the times, respectively. In conclusion, when the D14 BMA/B is used as a measure of early response, an absence of D7 PBB can reliably predict a negative BM, however persistence of PBB does not necessarily predict a sub-optimal BM response to early therapy. Therefore, patients without PBB on D7 may not require BMA/B on D14, therefore avoiding an invasive procedure for this group of patients.