the recent completion of an initial draft sequence of the human genome and with the evolving and enhanced view of environmentmental health, we will be able to conduct more precise studies of environmental contributions to cancer. He further suggested that we will need a new toolbox to address cancer resulting from the common modifier genes and multiple environmental exposures. In the charge to the speakers and participants, he outlined a number of questions that would begin to address what research tools will be needed, how new scientific information can be applied in a timely manner to reduce the burden of cancer, and how this can be flexible enough to treat the individual.

Sam Donaldson, of ABC News, opened the meeting with a keynote address in which he described the media’s tendency to seek out scientific outliers rather than the conventional wisdom. He urged the scientific community to be clear in its messages about the linkages between cancer and the environment and to emphasize areas of agreement.

THE ROLE OF THE ENVIRONMENT IN CANCER

In a scientific keynote address, Joseph Fraumeni, National Cancer Institute, highlighted the importance of environmental factors in human cancer. He pointed to a growing body of knowledge that dramatically illustrates the influence of such factors, for example, the observations of scrotal cancer among young chimney sweeps in London in 1775 and the international variation reported in cancer incidence. John Milner, Pennsylvania State University, using a broader perspective of environment—one that includes diet and lifestyle, described the evidence of dietary interactions and cancer. He discussed the findings that both essential and nonessential dietary nutrients can markedly influence several key biological events, including cell cycle regulation, processes involved in replication or transcription, immunocompetence, and factors involved in apoptosis, or programmed cell death. These observations suggest that specific foods or components may have the potential to markedly reduce cancer risk.

Analyses of the incidence of cancer in twin pairs and in families are traditional methods for answering questions about the relationships between cancer etiology, genes, and the environment. Kari Hemminki, Karolinska Institute, and Curtis Harris, National Cancer Institute, described recent progress in identifying and characterizing susceptibility genes in familial cancer. This work, taken together, has revolutionized our understanding of the critical genetic mechanisms in cancer etiology. Studies that combine genetic analysis with assessment of exposures and diet can explain why not everyone exposed to a particular cancer-causing chemical will develop cancer. Recent research has identified functional polymorphisms that influence an individual’s cancer risk and has focused on gene products involved in the activation and detoxification of carcinogens and DNA repair. Gene polymorphisms that are important in apoptosis will increasingly be recognized as clues to individual susceptibility to cancer.



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