Cancer and the Environment Gene-Environment Interaction (2002) / Chapter Skim
Currently Skimming:
2. Keynote Addresses
2. Keynote Addresses
Pages 11-24
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 11... ...
Keynote Addresses CANCER, THE ENVIRONMENT, AND THE MEDIA Samuel Donaldson I know a little bit about cancer and the environment, because I am a member of the cancer club the melanoma branch and since receiving this diagnosis, I have paid more attention to developments in cancer research than I did in the past. We have learned a lot about the effects of the environment in causing cancer, in some cases, far too late.
|
From page 12... ...
I recently moderated a panel on global warming, during which young people were asking questions. One young lady asked this distinguished panel whether global warming was really occurring.
|
From page 13... ...
That helped me put the widely touted range of 3.5 to 9 into better perspective. It would also be useful if the general scientific community believes the outlier, or odd stepper, is really wrong, they should say it loud and clear, and avoid the tendency toward professional courtesy.
|
From page 14... ...
Fraumeni, Jr. For some time, the epidemiologic evidence has suggested that the bulk of cancer in the population is related to environmental exposures, which are broadly defined here to include lifestyle factors, such as smoking, nutrition, and reproductive variables.
|
From page 15... ...
Percivall Pott, a British surgeon, reported one of the earliest observations on environmental cancer.
|
From page 16... ...
The overall importance of the environment to cancer etiology can be roughly gauged by the international variation in statistics, gathered from the periodic volumes entitled Cancer Incidence in Five Continents, published by the International Agency for Research on Cancer. The differences between geographic areas with the highest and the lowest rates have ranged between 50- and 150-fold for melanoma and for cancers of the nasopharynx, prostate, and liver, to about 5fold for leukemia (Table 2-2~.
|
From page 17... ...
program, a number of cancers are continuing to show substantial average annual increases in incidence, including lung cancer among women due to cigarette smoking; melanoma due largely to sunlight exposure; pleural mesothelioma due to asbestos exposure; non-Hodgkin's lymphoma in part due to the AIDS epidemic, but largely unexplained; hepatocellular carcinoma due to hepatitis C virus infection; renal adenocarcinoma, particularly in African Americans, possibly related to increases in obesity and the prevalence of hypertension; and esophageal cancer. When we divided esophageal cancer by cell type, again using data from the SEER program, there was a remarkable increase in one cell type, esophageal iThe SEER program collects and publishes cancer incidence and survival data from 11 populationbased cancer registries and 3 supplemental registries covering approximately 14 percent of the U.S.
|
From page 18... ...
In the more recent maps, through 1994, there was a remarkable shift, with the elevated rates moving from the urban Northeast and coastal areas to broad stretches across the Southeast, a pattern that tracks the regional changes that have occurred in smoking habits. The earlier maps for lung cancer prompted a series of casecontrolled studies in the high-rate coastal counties, which drew attention to the unexpected scale and impact of asbestos exposures in shipyards, particularly those operating during World War II, and to synergistic interactions between asbestos and cigarette smoking.
|
From page 19... ...
Most remarkable have been the mortality patterns in China, where there is enormous geographic variation that has provided special opportunities to study environmental cancer. For example, the map for lung cancer among women revealed very high rates in the northeast, where case-control studies have implicated several indoor air pollutants as pulmonary carcinogens (such as cooking oil fumes from wok cooking, polycyclic hydrocarbons from coal-heating stoves, and indoor radon in poorly ventilated houses)
|
From page 20... ...
The greatest uncertainty at present is genetic or inherited susceptibility, but there is growing evidence that its overall impact on cancer risk is likely to be greater than previously estimated from the demographic patterns of cancer, the low levels of familial risk for common tumors, the low frequency of hereditary cancer syndromes, or the calculations based on twin studies that have sharply partitioned genetic from environmental factors. In addition, as we learn more about the role of genetic susceptibility and its pathways, we are likely to gain further insights into the cancer risks associated with common exposures, including dietary components, endogenous hormones, and environmental hazards, that are acted upon by functional variants of candidate genes.
|
From page 21... ...
As in other hereditary syndromes, the affected individuals often develop multiple primary cancers, including a predisposition to sarcomas associated with radiotherapy, indicating gene-environment interaction. The variety of tumors in this syndrome has helped to dispel an earlier notion that inherited susceptibility to cancer is site-specific or tissue-specific, and is thus in line with molecular studies suggesting that fundamental biological mechanisms controlling susceptibility and cell proliferation are shared by several, if not all, forms of cancer.
|
From page 22... ...
It also is important to ensure careful epidemiologic design with appropriate control groups, as well as highly accurate genotyping and exposure assessment, which may include acquired genetic biomarkers such as macromolecular adducts and mutational "fingerprints" of exposure. Any misclassification of the gene or the exposure will greatly decrease the power of the study and increase the sample size needed to show an effect.
|
From page 23... ...
The potential for population stratification, also known as ethnic confounding, can be handled in the main by appropriate epidemiologic techniques. In conclusion, the available epidemiologic evidence indicates that while environmental exposures drive the demographic patterns for most cancers, there are growing indications that gene variants may have a sizable impact on cancer development by modifying the effects of exogenous or endogenous risk factors and by helping to uncover low levels of relative risk from common exposures in genetically susceptible subgroups.
|
From page 24... ...
The big challenge for epidemiology now is to develop strategies to ensure that the advances in human genomics are incorporated appropriately into population studies as well as family-based and hybrid studies (consisting of population and family-based components) and that these studies have the power and sensitivity to dissect the environmental and genetic influences on cancer risk.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.