An example of how targeted therapies work is the mail system. A mailed letter goes through many steps in order go from point A to point B. If one of these steps is interrupted, the mail does not arrive. Targeted therapies interfere with a step that allows a cancer cell to get the message to grow and divide. Without the message the cell dies. When enough cells die, a cancer tumor shrinks.

Targeted therapies are usually given one at a time. For example, if a tumor has mutation A, B, & C, the mutation that is expected to causing the most growth is targeted first. Targeted drug #1 for mutation A; #2 for mutation B, and so on. Researchers are gathering information to see how different mutations can be targeted at the same time.

Many people are living longer and with better quality of life than would have been possible 5 years ago. This news is encouraging for patients, healthcare providers, and researchers.