Immunotherapy is a cancer treatment that helps your immune system fight cancer. It is a type of biological therapy. Biological therapy uses substances that are made from living organisms, or versions of these substances that are made in a lab. Doctors don't yet use immunotherapy as often as other cancer treatments, such as surgery, chemotherapy, and radiation therapy. But they do use immunotherapy for some types of cancer, and researchers are doing clinical trials to see whether it also works for other types. When you have cancer, some of your cells begin to multiply without stopping. They spread into the surrounding tissues. One reason that the cancer cells can keep growing and spreading is that they are able to hide from your immune system. Some immunotherapies can "mark" your cancer cells. This makes it easier for your immune system to find and destroy the cells. It is a type of targeted therapy, which uses drugs or other substances that attack specific cancer cells with less harm to normal cells. Other types of immunotherapies work by boosting your immune system to work better against cancer.

Use of techniques, biologically active substances, and procedures to enhance or restore the ability of the host immune system to fight cancer. Also used to lessen adverse effects that may be caused by some cancer treatments.

Immunotherapy is used to stimulate the body's immune system against cancer. These treatments target specific genetic characteristics of the tumor cells. The genetic characteristics of tumors do not depend on what organ in the body the cancer develops. So these drugs may be effective against many types of cancer.