Immunotherapy is also sometimes called biological therapy or biotherapy. It is a treatment that uses certain parts of the immune system to fight diseases such as cancer. This can be done by stimulating your own immune system to work harder or smarter to attack cancer cells or by giving you immune system components, such as man-made immune system proteins. Immunotherapy seems to work better for some types of cancer than for others. It is used by itself to treat some cancers, but for many cancers, it seems to work best when used along with other types of treatment. Monoclonal antibodies are man-made versions of immune system proteins. Antibodies can be very useful in treating cancer because they can be designed to attack a very specific part of a cancer cell. Cancer vaccines are substances put into the body to start an immune response against certain diseases. We usually think of them as being given to healthy people to help prevent infections. But some vaccines may help prevent or treat cancer. Non-specific immunotherapies boost the immune system in a very general way, but this may still result in more activity against cancer cells.