and either makes helper factors that stimulate the rest of the immune system or makes killer factors that destroy tumor cells .
Tumor vaccines depend on stimulating T cells in the body. But another approach is to take T cells out of a patient's body— either from the bloodstream or from within the tumor itself—make more of them and at the same time stimulate them with IL-2 , then return them in greater numbers than the patient could generate by himself or herself.
Although this approach is in its early stages, there have been some promising results in animals and in early studies with humans. Once again, melanoma and kidney cancer seem to be the most readily affected. As additional T cell growth factors are produced by genetic engineering, it should be possible to do a better job of growing T cells outside the body and causing them to be more highly activated than is now possible with IL-2 alone.
Tumor Vaccines One type of immunotherapy that has been studied for years and is only now coming of age is "active specific immunotherapy," more commonly known as the use of tumor vaccines. These would in theory work the same way as vaccines for measles, smallpox or other diseases.
The major difference in cancer treatment is that vaccines are used after someone has cancer. The vaccines are given to prevent recurrences or to get the body to reject tumor lumps, both of which are more difficult than
