Classification of cancer

Classification of cancer

• Tumors can be classified by
  • Anatomic site
  • Histology
    • Grading severity
  • Extent of disease
    • Staging
• Classification systems provide a standardized way to
  • Communicate with health care team
  • Prepare and evaluate treatment plan
  • Determine prognosis
  • Compare groups statistically
• Anatomic site classification
  • Identified by tissue of origin
  • Carcinomas originate from
    • Embryonal ectoderm (skin, glands)
    • Endoderm (mucous membrane of respiratory tract, GI and GU tracts)
  • Sarcomas originate from
    • Embryonal mesoderm (connective tissue, muscle, bone, and fat)
  • Lymphomas and leukemias originate from
    • Hematopoietic system
• Four grades of abnormal cells
  • Grade I
    • Tumor limited to tissue of origin; localized tumor growth
  • Grade II
    • Limited local spread
  • Grade III
    • Extensive local and regional spread
  • Grade IV
    • Cells are immature and primitive and undifferentiated
    • Cell of origin is difficult to determine
    • Metastasis
• TNM classification system
  • Anatomic extent of disease is based on 3 parameters:
    • Tumor size and invasiveness (T)
    • Spread to lymph nodes (N)
    • Metastasis (M)
• Staging
  • Performed initially and at several evaluation points
    • Clinical staging
      • Done at completion of diagnostic workup to guide effective treatment selection
        • Bone and liver scans, ultrasonography, CT, MRI, PET scans
    • Surgical staging
      • Determined by surgical excision, exploration, and/or lymph node sampling
      • Exploratory surgical staging is being used less frequently