Prognostic Factors in Acute Lymphoblastic Leukemia

Prognostic Factors in Acute Lymphoblastic Leukemia (ALL)

• Worse Prognosis Factors:

  • Age younger than 2 years, linked to infantile ALL and MLL gene translocations.
  • Presentation in adolescence or adulthood correlates with poorer outcomes.
  • Peripheral blood blast counts exceeding 100,000 indicate high tumor burden.

• Favorable Prognostic Markers:

  • Age between 2 and 10 years associated with better prognosis.
  • Low white blood cell counts are indicative of a favorable outcome.
  • Hyperdiploidy and trisomy of chromosomes 4, 7, and 10 also relate to improved prognosis.
  • Detection of t(12;21) is linked to better survival rates.

• Residual Disease Detection:

  • Molecular analysis of residual disease post-therapy predicts worse outcomes in both B-ALL and T-ALL, guiding clinical trial design.

Chronic Lymphocytic Leukemia (CLL) and Small Lymphocytic Lymphoma (SLL)

• CLL is the most prevalent leukemia in adults in the Western world, with around 15,000 new cases annually in the U.S.

• Median diagnosis occurs at age 60, with a male-to-female ratio of 2:1.

• CLL/SLL is rarer in Asian populations compared to Western countries.

• Pathogenesis:

  • Common genetic abnormalities include deletions of chromosomes 13q14.3, 11q, 17p, and trisomy 12q.
  • The deleted region on chromosome 13 may involve microRNAs miR-15a and miR-16-1, potentially acting as tumor suppressors.
  • Possible cell origins include post-germinal center memory B cells or naive B cells.
  • Deep sequencing of CLL genomes shows NOTCH1 receptor mutations in 10% to 18% of cases, alongside frequent RNA splicing gene mutations.

• Immunophenotype:

  • CLL/SLL cells express pan B-cell markers (CD19, CD20), CD23, and CD5, which is found on a small subset of normal B cells.

Hodgkin Lymphoma (HL)

• Arises from germinal center B cells and is frequently associated with Epstein-Barr Virus (EBV), particularly in mixed-cellularity subtype.

• EBV detected in 70% of mixed-cellularity cases; its transformation is linked to clonal expansion.

• The inflammatory microenvironment includes cytokines like IL-5, TGF-β, and IL-13 that may stimulate growth and attract cells.

• Immune Evasion:

  • Hodgkin Lymphoma employs mechanisms to evade T cell responses, including high expression of PD ligands (PD-L1 and PD-L2), often amplified on chromosome 9.

• Clinical Features:

  • Characterized by painless lymphadenopathy; confirmed only via tissue biopsy.
  • Younger patients with more favorable subtypes often present at stage I or II without significant “B symptoms” (fever, weight loss, night sweats).

Lymphoid Neoplasms: Definitions and Classifications

• Leukemia vs. Lymphoma:

  • Leukemia denotes widespread bone marrow and peripheral blood involvement, while lymphoma refers to discrete tissue mass neoplasms.
  • Lymphomas can sometimes exhibit leukemic presentations; progression to leukemia is common.
  • Terms reflect typical disease distribution at presentation.

• Hodgkin vs. Non-Hodgkin Lymphoma:

  • Hodgkin lymphoma has unique pathological features and distinct treatment protocols compared to non-Hodgkin lymphomas (NHLs).
  • Plasma cell neoplasms are a special category, primarily arising in bone marrow with rare peripheral involvement.

• Presentation:

  • Two-thirds of NHLs and all Hodgkin lymphomas typically present as enlarged nontender lymph nodes (>2 cm).
  • One-third of NHLs may present with symptoms from extranodal site involvement (e.g., skin, stomach, brain).
  • Symptoms in lymphocytic leukemia arise from normal hematopoiesis suppression by tumor cells.
  • Multiple myeloma, a common plasma cell neoplasm, leads to bone destruction and pain due to fractures, alongside symptoms from secreted tumor proteins.

This quiz focuses on the prognostic factors associated with Acute Lymphoblastic Leukemia (ALL). It includes discussion on various age groups, blood count thresholds, and their implications on patient outcomes. Test your knowledge of what influences prognosis in ALL.