When it was announced that former President Jimmy Carter had been diagnosed with cancer that had spread to his liver and brain, there wasn't much optimism for his outcome. A few months later that changed when he announced that, after a course of highly specialized immunotherapy, his cancer was gone. How did this reversal take place?
Immunotherapy works because unlike chemo or radiation, where substances are introduced to kill cancer cells (and often kill healthy cells as well), cancer cells are attacked instead by the body's own immune system. President Carter's treatment was personalized to his immune system, a crucial part of immunotherapy. Each person's cancer and immune system reacts differently but finding the "sweet spot" of therapy that can kick the immune system into gear is the goal of immunotherapy. In Carter's case it worked just as it should and hopefully as more research is done, it can be used in more cases.