Radioimmunotherapy (RIT) is a type of cancer treatment that combines radiation therapy and immunotherapy. It uses a monoclonal antibody that specifically targets cancer cells, and attaches a radioactive substance to it. When the antibody binds to the cancer cells, the radiation emitted by the radioactive substance kills the cancer cells. Radioimmunotherapy is typically used to treat cancers that are difficult to treat with other methods, such as non-Hodgkin's lymphoma. It can also be used to treat solid tumors, including breast cancer and prostate cancer. The advantage of radioimmunotherapy is that it can specifically target cancer cells while minimizing damage to healthy cells, unlike traditional radiation therapy which can damage healthy cells as well. However, radioimmunotherapy can have side effects such as low blood counts and immunosuppression, which can make patients more vulnerable to infections. As with any cancer treatment, the best approach will depend on a number of factors, including the type and stage of cancer, the patient's overall health, and other individual factors.