There are many types of cells that make up every tissue in your body. For example, there are blood cells, brain cells, and skin cells. Each type has its own job. Cancer starts when certain genes in healthy cells change and become abnormal over time. This change is called a genetic mutation.

Genes tell cells how to make proteins to keep the cell working. If the genes mutate, these proteins change, too. This can make cells divide too much or too quickly and allow the cells to live much longer than they normally would. When this happens, the cells grow out of control and form a tumor. Learn more about the genetics of cancer.

To develop targeted therapies, researchers first identify the genetic changes that help a tumor grow and change. A potential target for this therapy would be a protein that is present in cancer cells but not healthy cells. This can be caused by a mutation. Once researchers have identified a mutation, they develop a treatment that targets that specific mutation.

Targeted therapies can do different things to the cancer cells they target:

• Block or turn off signals that tell cancer cells to grow and divide

• Prevent the cells from living longer than normal

• Destroy cancer cells

To best match the best targeted therapy for your tumor, your doctor may order tests to learn about the genes, proteins, and other factors that are unique to your tumor. This helps find the most effective treatment. Like other treatments, targeted therapies can cause side effects, so it is important that your doctor matches your tumor to the best possible treatment and dose. The dose of targeted therapy that you will receive is based on many factors, like your body weight and your risk of developing severe side effects. Talk to your health care team about why they recommended a certain dose.