Cancer vaccines are a type of immunotherapy that aim to stimulate the body's immune system to recognize and attack cancer cells. These vaccines can be used as a preventive measure to reduce the risk of developing cancer, or as a treatment to help the body fight existing cancer. They work by training the immune system to target specific proteins or antigens found on cancer cells, triggering an immune response to destroy them. Cancer vaccines can potentially be used in combination with other cancer treatments, such as chemotherapy or radiation therapy, to improve outcomes for patients with a variety of cancers. Research in this area is ongoing to develop new and more effective cancer vaccines for a wide range of cancer types.