Two New Observational Studies Suggest Future Directions in Lung Cancer Chemoprevention

either nutrients or drugs that delay or prevent the development of cancer. Hormonal manipulations have at least some efficacy for breast and prostate cancers and colorectal adenomas are decreased by cyclooxygenase inhibitors, although the effect of these drugs on colorectal cancer is not clear. There are no effective chemopreventive agents for lung cancer. Interestingly, Saccomanno, who pioneered sputum cytology, published the first lung cancer chemoprevention trial, using cytology as an intermediate endpoint, in 1982 (2). Observational and in vitro studies strongly suggested that retinoids would be effective for lung cancer chemoprevention, but when beta carotene and other retinoids were studied in randomized controlled trials, a harmful (20% increase in lung cancer) effect was surprisingly found (3, 4). These studies were an expensive, but valuable, lesson in that following what was the commonly held assumption that retinoids would be protective without a prospective trial would have certainly increased lung cancer deaths.