Tumors grow because the body's defense mechanisms have not been turned on or are turned off by the cancer cells. Dr. Thibodeau is developing vaccines that could alarm the immune system to the presence of developing tumors. Fragments of cancer cells are injected to the patients and the research aims at determining the best formulation for such vaccines. Indeed, it is crucial to target the vaccine to the white blood cells that are responsible for the initiation of immune responses. This procedure will activate the most proficient defence mechanisms against already established tumors such as melanomas.