Prognosis of very late relapse in children with ALL: Results of KYCCSG study, ALL-96 and ALL-02

Abstract

[Background] The prognosis of children with acute lymphoblastic leukemia (ALL), who relapsed after a long period from the cessation of the initial treatment, is uncertain, and no treatment strategy has been fully established. [Methods] We analyzed the prognosis of patients who relapsed more than 24 months after the discontinuation of the treatment (very late relapse, VLR) in the KYCCSG protocols, ALL-96 and ALL-02. [Results] A total of 357 patients were enrolled in the two studies and 70 patients (19.6%) relapsed. Eight patients (2.2%) developed VLR with a median remission duration of 37.5 (range, 26–42) months after the cessation of the treatment. At the time of initial diagnosis, six patients were classified into the standard-risk group and two patients into the high-risk group. The sites of relapse were isolated bone marrow (BM) in six patients, isolated testis in one, and a combination of both BM and central nervous system in one. All the eight patients achieved a second complete remission (CR) after reinduction chemotherapy. Three of the eight patients received allogeneic stem cell transplantation (allo SCT). However, one of the three patients had another hematological relapse 11 months after the allo SCT and died. Five patients were successfully treated with chemotherapy only, and therefore, seven patients are alive in CR with a median follow-up duration of 57 (range, 32–92) months after their relapse. [Discussion] Our study indicated that the incidence of VLR is approximately 2%, which is similar to those of previous reports. All patients achieved a second CR after reinduction chemotherapy and seven of the eight patients are alive in CR without a second relapse. Our data suggests that the prognosis of patients with VLR of childhood ALL is favorable.