Pneumocystis carinii pneumonia during maintenance treatment of childhood acute lymphoblastic leukemia

Background. Pneumocystis carinii pneumonia (PCP) is a wellknown risk among patients with deficient T-cell function such as children treated for acute lymphoblastic leukemia (ACL). The purpose of this study was to estimate the risk for PCP during maintenance treament (MT) to identify patients at risk who could benefit from prophylaxis. Procedure. We registered all episodes of PCP during MT in 71 children diagnosed between January 1992 and June 1997 with non-fi-cell ALL at The Copenhagen University Hospital. Sulphametoxazole and trimetroprim (SMX/TMP) prophylaxis against PCP was given during induction and consolidation therapy but stopped prior to MT with oral methotrexate/6-mercaptopurine. Patients with standard (SR), intermediate (IR), and high risk (HR) ALL started MT at 3, 8, and 15 months from diagnosis, respectively. Results. The HR group had a cumulated risk of 70% for developing PCP, whereas the risk for PCP in children with IR and the SR was 11 and 8%, respectively (P < 0.0001). All but one of these 13 cases of PCP occurred within 8 months after cessation of SMX-TMP prophylaxis. Conclusion, The higher incidence of PCP among HR compared to non-HR patients following cessation of SMX/TMP prophylaxis probably reflects the significantly longer T-cel[ suppressive consolidation therapy in this group. The very low incidence of PCP during the later part of MT emphasizes that methotrexate/6-mercaptopurine MT have more impact on B-cell than on T-cell function. TMP/SMX prophylaxis should be recommended for all children treated for ALL. (C) 2001 Wiley-Liss, Inc.