Cancer is a major health problem around the world. Each year one million people in the U.S. are diagnosed with cancer and more than a half a million people die. Cancer is second only to cardiovascular disease as the leading medical problem in the U.S. It is estimated that almost one third of Americans will be affected by cancer in their lifetime, and more than two-thirds of those individuals will die.

What is cancer?
It is actually a group of diseases that can appear in any tissue of the body and it involves uncontrolled growth of cells. The affected cells no longer grow normally and do not carry out their normal functions. Instead, they grow and divide, destroying the functional integrity of the tissues in which they are found and sometimes spread to other sites, producing further damage. The nucleus, which contains the genetic material, is potentially vulnerable to damage that can affect normal cell growth and differentiation (specialization). The genes readily affected by cancer-causing damage are the oncogenes and the tumor suppressor genes. A mutation of one of these genes, sometimes affecting only one chemical component of the gene, can set in motion the events that lead to cancer.

What causes cancer?
Environmental toxins are known or suspected to induce cancer. Tobacco, a highly carcinogenic (cancer-producing) agent, induces cancer directly and makes other carcinogens more dangerous. Many chemicals (and even some medications) have the potential to induce cancers. In addition, some viruses (some AIDS viruses, hepatitis B virus, Epstein-Barr virus, and human papilloma virus) can induce cancers. Some cells of the immune system, such as natural killer cells and other lymphocyte-derived cells, can potentially offer some protection against cancers, so it is not surprising that immunosuppressed patients have a higher incidence of some cancers. Individuals who are immunocompromised from stress also may have a higher incidence of some cancers, or perhaps the spread of already existing cancers. Radiation is known to induce some cancers, especially in high doses. Genetic susceptibility plays an important role in the onset of many cancers, with some genes (such as the breast cancer genes) predisposing the carrier to a higher likelihood of having that specific cancer. Screening for early detection of cancers and a search for specific markers that could provide early warning of susceptibility are important aspects of prevention and treatment of cancer.

The danger of free radicals
An obvious question asked by physicians and medical researchers is why radiation, some chemicals and many toxic agents induce cancer. A major culprit in this process is free radicals, highly reactive and unstable molecules that possess an unpaired electron associated with one or more atoms. When the free radical reacts with other molecules, in an attempt to achieve stability, it can do extensive damage to components of the cell, especially the genetic material in the nucleus. Free radical damage to the DNA induces mutations, leading to the uncontrolled proliferation of cells that characterizes cancer. Free radicals also can directly activate oncogenes (cancer genes). An additional type of damage done by free radicals is the conversion of some relatively harmless substances (pre-carcinogens) into dangerous cancer-producing chemicals (carcinogens). Furthermore, free radicals can interfere with cellular mechanisms that can potentially limit abnormal cell growth and also can interfere with immune defenses that could help keep the onset, growth and spread of cancer in check.

Anti-oxidants defend against free radicals
Anti-oxidants are a conspicuous first-line defense against free radicals and are able to counteract or at least slow all major steps in the process of free radical induction of cancer. Anti-oxidants also can induce cancer cells to kill themselves (called apoptosis, or cell suicide), and can boost aspects of immune responses that can limit metastases and help to eliminate some cancer cells. Sizable epidemiological literature indicates that a diet rich in fruits and vegetables that contains high amounts of anti-oxidants (vitamin C, beta-carotene, and bioflavonoids) reduces the incidence of a variety of cancers in both humans and animals. In humans, some of the more carefully done studies have reported that vitamin E, beta-carotene and selenium decrease the incidence of lung and stomach cancer, that selenium supplements decrease both the incidence and death rate of cancer in general by half, and that vitamin E supplements decrease the incidence of prostate cancer.

Not all studies involving anti-oxidants produce similar results. Study variations may include the types of anti-oxidants used, amount of the supplements, duration of treatment, inclusion criteria for the study and many other aspects of cancer. Long-term studies, in which a lifetime of anti-oxidant supplements is studied with regard to the incidence and progression of various cancers, are not available.

So at present, two points seem to be common sense. First, anti-oxidant supplements are a good idea across the life span. They clearly help counteract the damaging effects of free radicals, including the processes involved in the induction, growth, and proliferation of cancer. Second, when a person does encounter cancer, it is important to carefully investigate all available options including surgery, chemotherapy and radiation when indicated. It is important to not let promises of alternative therapies that have not been carefully tested to entice the person away from conventional medicine. Anti-oxidants are a great supplement and benefit, but should be used as an adjunct to and not as a replacement for conventional medicine.

David Felten, MD, PhD, is founding Director of the Center for Neuroimmunology and Professor of Pathology and Human Anatomy and Professor of Neurology at Loma Linda University School of Medicine in Loma Linda California. He is an internationally known researcher whose contributions helped to establish the field of psychoneuroimmunology.

© 2000 David L. Felten, M.D., Ph.D.

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