Cancer is one of the most common causes of death worldwide. It is a disease that begins as a renegade human cell over which the body has lost control. Since cell is involved, these we call ‘cancer cells’ continue to divide and multiply at their own speed which may form abnormal lumps or tumors. There are many types of cancer such as lung cancer, breast cancer, and brain cancer. Being a widely known cause of death, researches and experiments about cancer prevention or treatment have been presented. Cancer immunotherapy is the use of the immune system to reject cancer which is done by attacking the malignant tumor cells that are responsible for the disease. This can be either through immunization of the patient (e.g., by administering a cancer vaccine), in which case the patient’s own immune system is trained to recognize tumor cells as targets to be destroyed; or through the administration of therapeutic antibodies as drugs, in which case the patient’s immune system is recruited to destroy tumor cells. Antibody, also known as an immunoglobulin, is a large protein secreted by a plasma cell to be used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. Monoclonal antibody therapy is the use of monoclonal antibodies (or mAb) to specifically bind to target cells or proteins. This may then stimulate the patient's immune system to attack those cells. mAb therapy can be used to destroy malignant tumor cells and prevent tumor growth by blocking specific cell receptors. Antibodies are a key component of the adaptive immune response, playing a central role in both in the recognition of foreign antigens and the stimulation of an immune response to them. It is not surprising therefore, that many immunotherapeutic approaches involve the use of antibodies. The advent of monoclonal antibody technology has made it possible to raise antibodies against specific antigens such as the unusual antigens that are presented on the surfaces of tumors. Two types of monoclonal antibodies are used in cancer treatments: Naked mAbs are antibodies that work by themselves, have no drug or radioactive material attached to them, and are the most commonly used mAbs at this time; Conjugated mAbs are those joined to a chemotherapy drug, radioactive particle, or a toxin (a substance that poisons cells). These mAbs work, at least in part, by acting as homing devices to take these substances directly to the cancer cells. Conjugated mAbs are also sometimes referred to as tagged, labeled, or loaded antibodies. They can be divided into groups depending on what they are linked to mAbs with radioactive particles attached are referred to as Radiolabeled, and treatment with this type of antibody is known as radioimmunotherapy (RIT); mAbs with chemotherapy drugs attached that are referred to as Chemolabeled; and mAbs attached to cell toxins that are called Immunotoxins. A number of therapeutic monoclonal antibodies have been approved for use in humans by the U.S. Food and Drug Administration (FDA). Such as: trastuzumbab, brand name herceptin, which is humanized and is used for breast cancer treatment; alemtuzumbab, brand name campath, which is humanized and is used to treat chronic lymphocytic leukemia; and cetuximbab, brand name erbitux, which is chimeric and treats colorectal cancer which is a cancer in the colon or rectum. This research is for the further understanding on how cancer immunotherapy or prevention of cancer is done. The effects and how antibodies work inside our body will also be included on my research.