Immunotherapy is a treatment that boosts or manipulates the immune system to fight diseases, including cancer. For instance, by stimulating an immune response through vaccinations against viruses that cause cancers, like hepatitis B virus and human papillomavirus, these diseases can be prevented. Nonetheless, some cancer cells can avoid the immune system due to their rapid mutation and division. The immune response to many cancers involves three phases: elimination, equilibrium, and escape.

Efforts have been made to enhance the initial immune response with the goal of completely eliminating early-stage cancer and thus preventing escape. Promising methods such as cancer vaccines are under development. These vaccines aim to boost a person's anti-cancer immune response by introducing treated cancer cells into patients, leading to extended survival rates. The malignant melanoma and renal cell carcinoma vaccines have already shown positive results in clinical trials.

Despite its complexities, the immune system provides benefits that far outweigh its occasional failures. Cancer immunotherapeutics, which focuses on using immune responses to diagnose, monitor, and treat cancer, has become a focal point in research due to the often inadequate protection provided by immunity, as reflected by the yearly cancer mortality rate.

Immunotherapy plays a key role in the fight against cancer by helping the immune system act more effectively. Several types of immunotherapy exist, including immune checkpoint inhibitors, T-cell transfer therapy, monoclonal antibodies, treatment vaccines, and immune system modulators.

Immunotherapy has been approved for treating many types of cancer, but it is not yet as widely used as other treatments such as surgery, chemotherapy, or radiation therapy. Immunotherapy can be administered in different ways, including intravenous, oral, topical, and intravesical. The frequency and duration of treatment depend on several factors, including the type of cancer, its stage, the type of immunotherapy, and the patient's reaction to the treatment. Regular check-ups and medical tests are essential to measuring the effectiveness of immunotherapy.