- The term cancer encompasses a group of neoplastic diseases in which there is a transformation of normal body cells into malignant ones. This probably involves some change in the genetic material of the cells, deoxyribonucleic acid (DNA). oncogenes are the genes that organisms have evolved to regulate growth and repair of tissues. They are genetic codes for the proteins that function as signals that cells send and receive to regulate proliferation. These oncogenes are the targets of carcinogens. mutation and transformation of oncogenes may permanently affect a cell’s ability to control cell growth. Damage to the cell’s genetic material may be caused by carcinogenic agents. Normal cell lines can be transformed into cancer cells by viruses, chemical carcinogens, and radiation. Transformed cell lines have the ability to develop into malignant neoplasms. Transformed cells may also be recognized by other characteristics which include altered antigenicity, diminished contact inhibition, reduced requirements for certain nutrients, and the ability to grow in suspension. The altered cells pass on inappropriate genetic information to their offspring and begin to proliferate in an abnormal and destructive way. Normally, cells reproduce regularly to replace worn-out tissues, repair injuries, and allow for growth during the developing years. After these processes have taken place, cellular reproduction stops. Clearly the body in its normal processes regulates cell growth in an orderly manner. In cancer, there is no regulation and cell reproduction and growth is disorderly. The dangers of cancer are related to this chaotic reproduction of malignant cells.
- A disease affecting the growth rate of affected tissues, in which the control mechanisms of cells become altered and the cells divide to form neoplastic growths or tumours. ‘Benign’ tumours consist of well-differentiated cells similar to those in the surrounding tissues and are usually harmless unless located in regions where no operation is possible. ‘Malignant’ tumours are dangerous and usually contain embryonic cells, which are capable of floating away and forming new malignant growths in other sites.
