Acute Lymphoblastic Leukemia (ALL)

Acute lymphocytic leukemia (ALL) is also called acute lymphoblastic leukemia. The term acute means that the leukemia grows quickly, and if not treated, could be fatal in a few months. People with chronic leukemia can live years without treatment. Lymphocytic means it develops from early forms of lymphocytes, a type of white blood cell. This is different from acute myeloid leukemia (AML), which starts in other blood cell types found in the bone marrow. Neoplastic disease which results from a mutation in a single lymphoid progenitor cell at one of several discrete stages of development in B cell or T cell.

Epidemiology

• Most common childhood acute leukemia, ~80%
• Incidence in adults, ~20%
• Bimodal distribution of occurrence:
  • Peak at age 2-5
  • Second increased incidence after age 50

Risk factors of ALL

There are only a few known risk factors for ALL.

• Radiation exposure
• Exposure to certain chemicals
• Infection with certain viruses
• Certain inherited syndromes
• Having an identical twin who was diagnosed with ALL in the first year of life

Signs and Symptoms of ALL

• Generalized weakness and fatigue
• Anemia
• Dizziness
• Frequent or unexplained fever and infection
• Weight loss and/or loss of appetite
• Excessive and unexplained bruising
• Bone pain, joint pain (caused by the spread of "blast" cells to the surface of the bone or into the joint from the marrow cavity)
• Breathlessness
• Enlarged lymph nodes, liver and/or spleen
• Pitting edema (swelling) in the lower limbs and/or abdomen
• Petechiae, which are tiny red spots or lines in the skin due to low platelet levels

Pathophysiology

• Acquired Genetic Change in Chromosome
  • Change in number, ie ploidy
  • Change in structure
    • Translocations (most common)
    • Inversions
    • Deletions
    • Point mutations
    • Amplifications

Classification

Immunologic Subtype	% of cases	FAB Subtype	Cytogenetic Abnormalities
Pre-B ALL	75	L1, L2	t(9;22), t(4;11), t(1;19)
T cell ALL	20	L1, L2	14q11 or 7q34
B cell ALL	5	L3	t(8;14), t(8;22), t(2;8)

Treatment

• Remission Induction
• Intensification (Consolidation) Therapy
• Maintenance Therapy
• CNS Prophylaxis
• Allogeneic Stem Cell Transplant

Relapse and Prognosis

Relapse

• Most occur during treatment or within the first 2 years
• Bone Marrow is the most common site
• Poor prognostic factors in patients previously treated:
• Relapse on therapy
• Short initial remission after intense therapy
• T-cell immunophenotype
• Ph Chromosome
• Circulating blasts
• High leukocyte count at relapse

Prognosis

• Overall better in children than in adults
• In adults, worse outcomes with
  • Increasing age, >60
  • Increased wbc count at presentation