We analysed 7 cases of childhood ALL who survived for more than 3 years after the first relapse: 4 cases with bone marrow relapse, and 3 with CNS relapse. ALL cases were standard risk ALL in terms of initial WBC count, age at onset, and mediastinal mass. The ratio of males to females was 5 to 2, and all cases relapsed in bone marrow were male.
Of 4 cases with BM relapse, two were followed by CNS relapse despite of the previous intrathecal administration of MTX or CA. The other two developed the second bone marrow relapse 53 and 50 months later, respectively. Two cases who had CNS relapse in their late clinical course had not received CNS prophylaxis at onset. They were successfully treated with craniospinal irradiation. The remaining case who relapsed in the CNS subsequently experienced isolated testicular relapse. He was treated with bilateral castration, and is now on the replacement therapy of androgen once by 2 or 3 months.
From these findings, it appears that a fraction of patients who relapse either in the bone marrow or other sites in their late clinical course will survive long thereafter only with conventional chemotherapy. Further studies based on immunological and biological approach are required to dissect these patients who seems to be a unique subset of ALL.
