Monthly pulses of vincristine and prednisone prevent bone marrow and testicular relapse in low-risk childhood acute lymphoblastic leukemia: a report of the CCG-161 study by the Childrens Cancer Study Group.

On study CCG-161 of the Childrens Cancer Study Group (CCSG), 631 children with acute lymphoblastic leukemia (ALL) at low risk for relapse were randomized to receive monthly pulses of vincristine-prednisone (VCR-PDN ) during maintenance therapy in addition to standard therapy with mercaptopurine (6MP) and methotrexate (MTX), and either cranial irradiation during consolidation or intrathecal (IT) MTX every 3 months during maintenance. All patients received six doses of IT MTX during induction and consolidation. With a minimum follow-up time of 4.25 years, 76.7% receiving VCR-PDN were in continuous complete remission at 5 years, in contrast to 63.9% receiving GMP-MTX alone (P = .002). The difference in relapse-free survival was due primarily to bone marrow relapse (P = .0008), and in boys also to testicular relapse (P = .003). Among the nonirradiated patients, the 5-year disease-free survival (DFS) was 79.4% for patients randomized to the VCR-PDN pulses, in contrast to 61.2% for the patients randomized to receive 6MP-MTX alone (P = .0002). Among the irradiated patients, the DFS was not significantly different. Of the four combinations of maintenance and CNS therapy studied, the highest DFS was achieved with VCR-PDN pulses and maintenance IT MTX.