Understanding Oncogenes
An oncogene is a mutated gene that helps change a normal, healthy cell into a cancer cell. These are the two types of oncogenes.
Inherited oncogenes. These mutated genes can be passed down from the mother, the father, or both parents. When a fertilized egg that carries the gene with the mutation divides, the mutation is found in almost all cells of the baby’s body. That means inherited mutations are found not only in tumors but also in many other cells.
Only about 5 to 10% of people (or 5 to 10 of 100 people) who get cancer have inherited oncogenes. One common one is the RET gene. This gene is linked to multiple endocrine neoplasia syndrome, which is a cancer syndrome of the endocrine system.
Tumor-specific oncogenes. These mutated genes are found only in tumors, not in other cells in the body. These oncogenes are not inherited. As cells grow and divide, genetic changes may occur and make one cell grow too quickly. When these cells divide and multiply, they genetically alter future cells. Sometimes those cells die. Sometimes those cells develop cancer. Usually, genetic changes alone do not cause cancer. It most often takes another factor, such as sun exposure, diet, or smoking, for cancer to start. Genetic changes like this are known as somatic mutations. As scientists learn more about them, these oncogenes may help doctors plan a patient’s cancer treatment. They may also be used to predict prognosis.