How is relapsed pediatric acute lymphoblastic leukemia (ALL) treated?

Updated: Jan 02, 2019
  • Author: Vikramjit S Kanwar, MBBS, MBA, MRCP(UK), FAAP; Chief Editor: Jennifer Reikes Willert, MD  more...
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Relapse occurs in 20% of children with ALL, when blasts reappear after complete remission (CR) is achieved. The site of relapse in the vast majority of cases involves the bone marrow, but other sites include the CNS or testes. Isolated CNS relapse (< 5% of total relapse) or isolated testicular relapse (1-2% of total relapse) is rare with current ALL therapy, but if it occurs more than 18 months from diagnosis, it has good outcome with local and aggressive systemic chemotherapy. Patients at high risk for further relapse and poor survival are those with B-lineage ALL with early relapse in bone marrow (which may be combined with other sites, such as CNS) or all T-lineage ALL. [23]

Early relapse is defined as bone marrow relapse that occurs within 36 months of initial diagnosis or within 6 months of completion of primary therapy; outcomes are poor, with only 35-40% of these patients achieving long-term remission. Late relapse occurs outside this time frame, and outcomes are better than for early relapse, with over half of these patients achieving long-term remission. Unfortunately, the vast majority of patients with T-lineage ALL suffer early relapse.

In patients with relapsed ALL, a multidrug-resistant clone has been selected so that leukemia cells are more resistant to chemotherapy. [24] Nevertheless, patients often respond to the same agents initially used for induction; the problem is in keeping them in remission. Standard treatment phases for ALL with first relapse is reinduction chemotherapy to get patients back into remission (CR2), followed by postreinduction consolidation therapy for patients who achieve CR2, discussed below.

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