Radioimmunotherapy (RIT) is a type of cancer treatment that combines the targeted delivery of radiation with the specificity of monoclonal antibodies. The basic principle behind RIT is to use a monoclonal antibody, which is a laboratory-produced protein that targets a specific protein or antigen present on the surface of cancer cells. These monoclonal antibodies are designed to recognize and bind to cancer cells, delivering a lethal dose of radiation to the cancer cells without affecting normal cells. The basic steps involved in RIT are as follows: Firstly, a patient is injected with a radioactive substance that is attached to a monoclonal antibody. Once inside the body, the monoclonal antibody attaches itself to the cancer cells, delivering radiation directly to the tumor site. The radiation emitted from the radioactive substance kills the cancer cells by damaging their DNA. The use of RIT has several advantages over other forms of cancer treatment. The primary advantage is the ability to deliver a highly targeted dose of radiation directly to the tumor site, thereby minimizing the exposure of healthy tissues to radiation. This reduces the risk of side effects associated with traditional radiation therapy. Additionally, RIT has been shown to be effective in treating cancers that are resistant to other forms of treatment, such as chemotherapy. RIT is primarily used in the treatment of non-Hodgkin lymphoma, a type of cancer that affects the lymphatic system. The most commonly used monoclonal antibody in RIT for non-Hodgkin lymphoma is ibritumomab tiuxetan (Zevalin®). RIT has also been used in the treatment of other types of cancer, including breast cancer, ovarian cancer, and prostate cancer. Despite its benefits, RIT has some limitations. One of the major limitations is that it is not effective against all types of cancer. Additionally, RIT can cause some side effects, such as fatigue, nausea, and decreased blood cell counts. However, these side effects are generally less severe than those associated with traditional radiation therapy. In conclusion, radioimmunotherapy is a promising treatment option for cancer patients, particularly those with non-Hodgkin lymphoma. By delivering a highly targeted dose of radiation directly to cancer cells, RIT has the potential to be more effective than traditional forms of treatment, while minimizing the risk of side effects. Ongoing research is focused on improving the effectiveness and reducing the side effects of RIT, which may make it a more widely used form of cancer treatment in the future.