Outcome of very late relapse in children with acute lymphoblastic leukemia

Few data are available on the long-term outcome of children who present with a very late relapse of acute lymphoblastic leukemia, so treatment of these patients remains controversial. The present study was aimed at investigating clinical features and treatment outcome of children with very late relapse, diagnosed and treated in Italy in the last 20 years. All children diagnosed in Italian centers with a first relapse of acute lymphoblastic leukemia occurring >or= 60 months after attainment of first complete remission were included in this study. These relapses were diagnosed between 1982 and 1997. Ninety-three patients (58 males, 62.4%) had a first very late relapse occurring at a median time of 6.1 years (range 5.8 - 13.7 years) after the initial diagnosis. At a median follow-up time of 9.1 years after relapse, the overall 5-year survival (SE) and event-free-survival (SE) were 55.6% (5.2) and 39.5% (5.1), respectively. In multivariate analysis the site of relapse was the only significant predictor of duration of the second complete remission. Patients with isolated bone marrow relapse fared worse than those with combined or isolated extramedullary relapse [5-year event-free survival (SE) 24.5% (5.9), 51.3% (11.1) and 68.4% (10.7), respectively; (p=0.004)]. All 7 patients who underwent an allogeneic bone marrow transplantation from a matched related donor are alive in second complete remission. In this evaluation patients with a very late relapse isolated to the bone marrow had a poor outcome while re-treatment of extramedullary or combined relapse was associated with better cure rate. Our data suggest that patients with very late isolated bone marrow relapse should be treated intensively; bone marrow transplantation from a matched related donor may be indicated.