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Acute Lymphoblastic Leukemia (ALL)

An estimated 5760 new cases of adult lymphoblastic leukemia (ALL) were diagnosed in 2009.1 Leukemia is the most common malignancy in pediatrics; 80% to 85% of leukemia in children is ALL and represents 2400 new cases diagnosed each year. The peak incidence of adult and pediatric ALL is50 years and 5 years of age, respectively.2 The exact cause of ALL is unknown. Less than 5% of cases have been associated with inherited genetic syndromes (Down or Bloom syndrome) or with exposure to ionizing radiation and chemotherapeutic agents. In the development of B cells and T cells, various events occur to develop a competent immune system. In ALL, mutations occur in the development of B- and T-cell progenitors leading to dysregulated proliferation and clonal expansion.3

Patients can present with malaise, fever, weight loss, palpitations, bruising, petechiae, bone pain, and lymphadenopathy. Many symptoms will represent malignant cells replacing normal hematopoiesis. Electrolyte disturbances such as hyperkalemia, hyperphosphatemia, hyperuricemia, and hypocalcemia may occur. Patients with acute leukemias may experience tumor lysis syndrome (to be discussed later in this chapter). Upon physical examination, hepatomegaly, splenomegaly, and a mediastinal mass may be noted.4 Leukocytosis (WBC > 30,000-50,000/μL) confers a poorer prognosis, particularly in B-cell ALL.5 Other factors which confers poorer prognosis include age (> 30), immunophenotype (B lineage worse), Philadelphia chromosome (Ph+) disease, and CNS disease.3,5

Diagnosis is determined by evaluating the following—complete blood count (CBC) with differential, coagulation studies, bone marrow biopsy and aspiration, and lumbar puncture. Cytochemical studies, immunophenotyping, and cytogenetics are performed on bone marrow samples. A lumbar puncture should be performed to assess potential CNS involvement.4

A strong prognostic factor is patient's response to treatment. The primary goal of treatment is to induce and maintain a complete remission (CR). A CR can be induced in 96% to 99% of children and 78% to 93% of adults.6 Treatment of pediatric ALL is divided into the following phases: induction, consolidation, interim maintenance, delayed intensification, and maintenance. Adult ALL is divided into induction, consolidation, and maintenance. CNS treatment is performed throughout all phases of therapy. Intrathecal therapy consists of methotrexate and cytarabine which can be given alone or in combination.4 Patients with T-cell ALL have an increased incidence of CNS disease and should receive systemic high-dose methotrexate to penetrate the CNS.7 Multiple intensive chemotherapy regimens have been shown to provide benefit in adult ALL. Specific agents which are used in the treatment of ALL are summarized in Table 17-1.

TABLE 17-1 Commonly Used Agents in Treatment of ALL

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