Vaccines Health Article

Definition

A cancer vaccine is a method of treating the disease involving administration of one or more substances characteristic of the cancer, called antigens, often in combination with factors that boost immune function. This induces the patient's immune system to attack and eliminate the cancerous cells.

Purpose

Unlike traditional vaccines for infectious diseases, at this time cancer vaccines are not given to prevent the initial development of cancer. Instead, cancer vaccines are a method of treating cancer that has already occurred and are given to patients already diagnosed with cancer.

As a cancer treatment method, the ultimate goal of most cancer vaccines is the elimination of tumor or cancerous cells from the body. Other vaccines are given after the use of more traditional treatments, such as chemotherapy, radiation, or surgery, with the aim of suppressing the recurrence of the cancer.

Precautions

No vaccine has yet been approved by the Food and Drug Administration (FDA) for the treatment of cancer. Accordingly, vaccines are not standard treatments and other more traditional treatments should be investigated first. Vaccines are available only through participation in clinical trials. Each trial has its own criteria that can limit who can participate. However, many cancers have a current trial for one or more types of vaccines. The American Society for Gene Therapy states that as of late 2000, vaccines were the most common approach to gene therapy being studied by researchers.

Most vaccine trials test the response of the disease with and without the vaccine or the effect of substances added to the vaccine, called adjuvants. Such trials usually only accept patients that have already tried the standard treatment methods. Others test a standard treatment method with and without the addition of the vaccine. A very few compare the standard treatment to the vaccine.

Looking at cancer vaccines overall, this treatment method has been more successful eliminating very small tumors rather than the getting rid of a large tumor load. So if the size of the tumor is significant, a more realistic goal is to shrink the tumor and reduce its effect on the patient's body, rather than total elimination of the cancer.

The complexity of the human immune system has made it very difficult to develop an effective vaccine. Tumors have strategies to evade detection by the immune system. Most notably, they mimic the outward appearance and antigens of the body's own cells. The immune system's built-in lack of response against "self" allows the tumor to escape notice by the body. Now fully aware of this phenomenon, researchers are working to develop methods of circumventing this problem to develop a highly effective vaccine system.