Coming of age - the chemoprevention of cancer

Article Abstract:

One approach to combatting cancer, which will become the leading cause of death in the US soon after the year 2000, is chemoprevention, the chemical prevention of cancer formation. Knowledge regarding cancer formation, or carcinogenesis, has grown; substances that normally appear in the diet, such as beta carotene and isotretinoin, have been cited as exerting preventive effects. Large, randomized studies of these chemicals are presented in the September 20, 1990 issue of The New England Journal of Medicine. Results for the two substances differ, however: beta carotene did not lower the rate of development of new basal-cell or squamous-cell skin cancer, while isotretinoin did appear to lower the rate at which second primary tumors developed in patients already treated for oral cancer. One explanation for the lack of effectiveness of beta carotene could be related to the large doses used in the study; they may have interfered with other nutrient substances. Evidence for related effects is presented. Isotretinoin was found to prevent second tumors, and is likely to work against primary tumors, as well. ''Field cancerization'', the idea that a whole area of the body undergoes a carcinogenic insult and becomes vulnerable to malignancy, is discussed. Chemoprevention studies ideally use intermediate markers of genetic, biochemical, and immunologic function, rather than waiting the long time that may be required for cancer to develop. A limited number of chemopreventive agents has been selected for study, partly because normal (or almost normal) volunteers do not want to suffer aversive side effects. These agents include beta carotene, retinoid compounds (of which isotretinoin is a member), folic acid, and vitamins C and E. A vast array of potentially chemopreventive agents from dietary sources awaits testing, and the National Cancer Institute has organized a decision-making structure to select the most promising. Currently, several large-scale trials of different substances are in progress, involving more than 100,000 subjects. The results could dramatically influence the way cancer is managed. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Research, Cancer, Cancer prevention, Diet, Diet in disease, editorial

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Comparison of low-dose isotretinoin with beta carotene to prevent oral carcinogenesis

Article Abstract:

Low-dose isotretinoin therapy appears to be significantly more effective than beta-carotene in preventing leukoplakia from progressing to oral cancer. Leukoplakia is a precancerous condition marked by white patches on the mucous membranes of the mouth. It is strongly linked to tobacco use. In a two-phase study, 70 patients with leukoplakia all underwent high-dose isotretinoin therapy for three months. In the second, maintenance-therapy phase of the study, in which 59 of the original patients participated, 33 took beta-carotene and 26 took low doses of isotretinoin. The rate of disease progression was 55% among patients taking beta-carotene compared with 8% among patients taking low doses of isotretinoin. Furthermore, the toxicity associated with low-dose isotretinoin therapy was fairly low.

Drug therapy

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Chemoprevention as a form of cancer control

Article Abstract:

Oral cancer control includes primary prevention, early detection and chemoprevention. Oral cancer often occurs in males 50 years of age or older with a history of tobacco use, at twice the rate of females. Alcohol adds to the carcinogenic effect of the tobacco. Meticulous, regular oral exams are necessary for individuals previously treated for oral cancer. Clinical, biochemical, histological and molecular changes that occur before malignancy are noticeable. Because surgery is not always the best treatment of leukoplakia, chemoprevention is also an important option. Prevention of any progression to malignancy is critical. It also gives protection against field cancerization. Health care professionals must continue to educate patients about the dangers of tobacco use.

Chemotherapy, Mouth cancer

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