Carcinoma Development ~ Cancer Grading/Staging ~ Symptoms of Cancer

Development of epithelial malignancy

An outline of the development of an epithelial malignancy, i.e. carcinoma, which is most definitely malignant is written below:
  1. The epithelium on the basement membrane is normal with the lymphatics and blood vessels normally positioned below the membrane.
  2. Random dysplasia in the cells (change in their structures) causes them to have abnormally large nuclei with injured DNA. The cells, however, are not yet malignant.
  3. Carcinoma in situ is the next step, where further DNA injury transforms the cells into a malignancy which cannot yet metastasize.
  4. The carcinoma in situ becomes an early invasive carcinoma, where additional DNA damage produces malignant cells that penetrate the basement membrane.
  5. The carcinoma cells then invade the blood vessels and lymphatics beneath the penetrated basement membrane, and distant metastasis occurs. NOTE: Metastasis means that cancerous cells have reached another part of the body via travel through the blood and lymph. Once the size of the metastatic tumor exceeds 2cm in diameter, the tumor secretes tumor-angiogenesis factor, which causes blood vessels to send out new capillaries. Areas with high blood supply, e.g. brain, bone, lungs, adrenal glands and liver, are mostly susceptible to metastasis.

Grading and staging of a tumor

Before being treated, each individual's cancer is graded based on the degree of differentiation between affected cells. Grading is, in other terms, a way to determine the degree of anaplasia. Anaplasia, itself, is defined as a condition in which the cells are poorly differentiated (meaning they are unlike each other). Cancer is also staged, which describes the location and pattern of spread of a tumour within the host. Staging is influenced by:
  • Tumour size
  • Extent of local growth
  • Lymph node/organ involvement
  • Presence of distant metastasis
The grades for which cancers are classified include:
  • Grade Ⅰ: well-differentiated
  • Grade Ⅱ: moderately differentiated
  • Grade Ⅲ: poorly differentiated
The stages for which cancers are classified include:
  • T staging: tumor size (0-3)
  • N staging: number of lymph nodes affected (0-2)
  • M staging: number of metastases (0-X)

Behaviour of cancer cells

  • Proliferate, regardless of space availability or presence of growth promoting factor
  • Make and respond to own growth factors (removed from feedback control)
  • Reduced number of gap junctions
  • Do not adhere and easily shed into surrounding tissue, blood and lymph

How are cancer cells destroyed?

  • Cellular mechanisms: natural killer cells, B-lymphocytes, helper T-lymphocytes and cytotoxic T-lymphocytes → becomes difficult when cancer cells resemble ancestors and are not recognised as 'non-self'
  • Radiation therapy
  • Chemotherapy

Symptoms of cancer

Every cancer is different, but common symptoms include:
  • Pain
  • Cachexia, an overall weight loss and generalised weakness
  • Bone marrow suppression
  • Anaemia (low red blood cell count)
  • Leucopoenia (low white blood cell count)
  • Thrombocytopoenia (low blood platelet count)


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