Learning Center Articles

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