Caroline Speed; Week 7 MED1011; Biochemistry
Some changes of cells may result in altered tissue invasiveness, angiogenic proliferation, ability to escape immune surveillance. Change from a normal cell to a cancer cell is cell transformation. Cancer cells have an enlarged nucleus, changes to cytoskeleton and loss of specialised features. There is a spectrum when it comes to cancer cell appearance changes. With some highly malignant cancers it is possible to tell the cell of origin. Benign tumours appear as in cell of origin, are localised, usually do not cause problems unless in a confined space. Malignant do not resemble tissue of origin, often have irregular structures, large variable nucleus, little cytoplasm, evidence of mitosis, little specialised structures and invade surrounding tissues.
Metastasis is spread to other parts of the body, is more common with some cancers than with others. This comes with the decreased ability of cancer cells to adhere to neighbouring cells. Cancer cells extend into surrounding tissue by degrading extracellular matrix (proteolytic enzymes). Require angiogenesis.
85% of all cancers are sarcomas from epithelial tissue, sarcomas are from bone, muscle, blood vessels, lymphoma from lymphoid cells. Cancer displaces and replaces normal tissue, decreasing function, can block vital passages, competes with normal cells for nutrition and blood supply (can cause cachexia). Cancers can secrete hormones that cause distant effects even when the cancer has not spread, called non-metastatic manifestations of cancer (lung cancer and cortisol). Metastasis can occur due to cancer tissue being trapped in blood vessel and migrating. Site of venous drainage often determines metastasis. Lung and liver have small capillaries so it is possible for large cancer cells to be trapped there easily, are main two sites of metastases. Breast and prostate cancer frequently get bone metastases which lead to hypercalcaemia (osteolytic lesions, fractures, osteoporosis). Cancer spread to bone can cause severe pain, weakens bone, causes deformities (nerve compression, spinal cord compression), hypercalcaemia.
Cancer dormancy can be from cancer presence without angiogenesis (tumour may survive but not expand).