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Chemoprevention strategies in lung carcinogenesis.

Chemoprevention entails using specific agents to suppress carcinogenesis and thereby prevent the development of primary or second primary cancers. Because the concept of chemoprevention in patients with or at risk of lung cancer is new, ongoing clinical trials are based on data from epidemiologic and preclinical research, as well as on results of chemoprevention studies in head and neck cancer. The latter studies have provided a model for such studies in lung cancer, considering the two diseases have a similar etiology and biology of field carcinogenesis. Beta-carotene, natural vitamin A, and the retinoids may be effective chemopreventive agents. However, chronic administration of such agents may be required to prevent the development of cancer. Results of chemoprevention trials in head and neck cancer have demonstrated effective inhibition of the development of second primary tumors with the synthetic retinoid 13-cis-retinoic acid; investigators are hopeful this will be repeated in patients with lung cancer. Results of ongoing phase III trials and continued advances in the epidemiologic and biologic study of lung carcinogenesis should contribute to future research in this area.