CANCER AND PRECANCER PREVENTION: ORAL LEUKOPLAKIA PREVENTION
Leukoplakia is a condition characterized by white patches of tissue inside the mouth that are known to be premalignant. The major risk factors for leukoplakia are tobacco use, alcohol use, dietary factors, and the chewing of betel nuts. The highest rates of oral cancer are seen in India, Sri Lanka, Vietnam, New Guinea, the Philippines, Hong Kong, Taiwan, and parts of Brazil. In the United States there are about 32,000 cases of oral cancer.Patients who have been treated for and cured of their first cancer of the head and neck usually continue the same lifestyle, then develop and succumb to a second one.Certain nutrients, including retinoids, carotene, vitamin A, and vitamin E, have an important role in the prevention of oral cancer. These nutrients inhibit leukoplakia and other precancerous and cancerous lesions in animal studies and in human trials. In humans, the use of certain retinoids reversed leukoplakia, but it recurred once the retinoids were discontinued. Taking beta-carotene alone or in combination with vitamin A was found to decrease the incidence of damaged mucosal cells in populations at high risk for oral cancer.In India, patients with oral lesions were divided into three groups: the first group received 180 milligrams per week of beta-carotene alone; the second received beta-carotene plus vitamin A (100,000 IU per week); and the third group received a placebo. Six months after treatment, complete remissions were seen in 15 percent of group one, 27.5 percent of group two, and only 3 percent of group three. New appearances of leukoplakia were strongly inhibited. In another study, similar patients were given 200,000 IU of vitamin A per week for six months; 57 percent of them responded completely and also had a complete suppression of new leukoplakia.Of twenty-four patients with leukoplakia given 30 milligrams of beta-carotene daily, 71 percent responded completely after three to six months. The investigators of this study also showed that betacarotene enhanced the immune system by significantly increasing the number of killer cells as well as effecting smaller increases in other immune cells. Hence beta-carotene effectively inhibits the cancer process, is nontoxic, and is readily available.In another human study beta-carotene conclusively reversed leukoplakia. The results of this study suggest that beta-carotene may not protect the body from cancer until late, when a normal cell is about to be transformed into a cancer cell. This means that the initial actions triggered by a carcinogen may not be inhibited by beta-carotene as it is by other nutrients, but rather the carotene stops the transformation of the cell from a normal one to a malignant one.Very high doses of carotene taken by mouth appear to lower the blood concentration of vitamin E over a period of eight months, and other studies show similar findings. In these studies, the protective effect of beta-carotene was somewhat reduced, indicating that all of the antioxidants are needed to protect the cell.*43\360\2*
