Discontinuing chemoimmunotherapy in childhood acute lymphoblastic leukemia.

We examined the results of discontinuing therapy in Japanese children with acute lymphoblastic leukemia. Of the 209 patients in chemoimmunotherapy study, 120 (57.4%) had all chemotherapy stopped after 3 years of complete remission, and 72 (34.4%) reached the point of discontinuing immunotherapy after 5 years of complete remission. Of the 120 children removed from chemotherapy, 14 (11.7%) have relapsed, mainly in the extramedullary sites (5 testis, 5 bone marrow, 3 central nervous system, 1 bone); relapses occurred 1-23 months after cessation of chemotherapy (median 11 months). Boys had a higher post-chemotherapy relapse rate than girls (0.21 vs. 0.08, P less than 0.05). None of the 72 children removed from immunotherapy have yet relapsed. Long-term remission and possibly cure can be expected in approximately one half of newly-diagnosed Japanese patients. Moreover, the active immunotherapy could be of benefit to elimination of bone marrow relapses after cessation of chemotherapy in children with acute lymphoblastic leukemia.