Cancer is a frightening word. Every year, about a million and a half people in the United States are diagnosed with some form of cancer. Although many people are treated successfully, there is still no sure cure for cancer.
The tremendous efforts of scientists have led to the development of several anticancer drugs, and researchers have also experimented with vaccines to cure cancer. Cancer is actually many different diseases that affect many different organs in the body.
Normally, cells in the human body grow and reproduce in an orderly way. But cancer cells lack the controls that moderate the growth process, so they continue to multiply wildly. They compete with healthy cells for space and nutrients, and they may spread to distant parts of the body through the bloodstream or lymph channels.
There are differences between the usual vaccines against disease-causing organisms and cancer vaccines. First, a vaccine against an infectious disease such as polio produces an immune response that prevents a disease from occurring or makes it milder. A vaccine against cancer immunizes a person to stop the growth of the cancerous cells. Second, the familiar vaccines are made from antigens on microbes that the body~s immune system recognizes as foreign.
Normally, a person’s immune system does not attack its own cells, so how can an anticancer vaccine work?
Although cancer cells are the body~s own cells, and not foreign, researchers have discovered that cancer cells produce antigens that are different from those on healthy cells. To mount an attack on the cancer cells, the immune system must recognize the cancer cells as foreign. Scientists have identified a large number of different antigens in prostate, breast, colon, lung, and ovarian cancers, as well as in lymphoma (cancer of the lymph glands) and melanoma (a serious form of skin cancer).
Scientists use several methods to generate anticancer antibodies. One method involves using cancer cells that have been removed from the person’s body. Researchers treat the cells with adjuvants, which are special additives that boost an immune reaction, and then the mixture is ready for injection.
The problem with this method is that a vaccine has to be made specially for each individual because each cancer is different. Other approaches involve the injection of various substances that increase the production of antigen by the tumor, or cancerous growth, which in turn increases the person’s immune response.
One group of researchers has been testing a vaccine against prostate cancer, using cancer cell antigens that were manufactured in the laboratory. They attached the antigens to a carrier molecule and injected the vaccine into mice. The mice produced antibodies to the cancer cell antigens. When the researchers tested the vaccine on men who had surgery for prostate cancer, the men also produced antibodies. The scientists hope that the vaccine may prevent the cancer from occurring again.
Other researchers are testing different kinds of vaccines against melanoma. One vaccine is made from melanoma cells from different patients. These cells are grown in the laboratory, and a vaccine is made from a combination of antigens from the surface of the cancer cells. When people with melanoma were given the vaccine, they remained disease-free for more than twice as long as melanoma patients who did not receive the vaccine.” Skin cancer of the type known as melanoma is characterized by irregularities and changes in moles.
Cancer vaccines present many challenges. The cancer may suppress the immune system, so it might not produce antibodies in response to a vaccine. Tumors may be able to escape detection by the immune system, or they may ill immune system lymphocytes Although anticancer vaccines may not be effective for advanced cancer, scientists believe they can help in the earlystages of disease.
There is one positive thing. Because the vaccine against hepatitis B helps reduce deaths from liver cancer, it has been called the first anticancer vaccine.