Diet, Nutrition, and Cancer (1982) / Chapter Skim
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2 Cancer: Its Nature and Relationship to Diet
2 Cancer: Its Nature and Relationship to Diet
Pages 17-29
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From page 17... ...
are incapable of undergoing cell division; some (e.g., the cells of the marrow and the epithelial cells of the gut and skin) are actively dividing throughout our adult life; and others (e.g., the cells of the liver)
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From page 18... ...
During the early days of cancer research, many people hoped that all cancer cells would prove to be defective in one particular, common feature (e.g., in their ability to respond to a specific restraining signal received by all tissues) , but this now seems most unlikely.
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From page 19... ...
Cancers that arise in the progenitors of the circulating cells of the blood are called leukemias (if the abnormal cells are circulating) and lymphomas or myelomas (if the cancer affects lymphocytes that tend to be localized in the lymph nodes or the bone marrow, respectively)
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From page 20... ...
It is as if an early step had permitted uncontrolled growth and the operation of natural selection, which in turn allowed the progressive evolution of increasingly abnormal and more rapidly multiplying types of cells. Because the average cancerous growth will amount to many millions of cells before it becomes detectable, it may already have undergone considerable selection for the fittest variants arising spontaneously within the population.
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From page 21... ...
The most widely studied method for producing cancer is to expose an animal to repeated doses of any physical or chemical agent that damages DNA and causes mutations. In certain instances it has been possible to show that the cancers produced by these agents are indeed arising as the consequence of damage to DNA.
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From page 22... ...
For example, it is not simply a matter of forcing the initiated cell to divide quickly, because certain agents that provoke cell proliferation do not act as promoters. Most promoting agents (e.g., the irritant phorbol esters in croton oil)
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From page 23... ...
Thus, the incidence of both cancers in an industrialized country like Czechoslovakia is not nearly as high as it is in New Zealand, which has one of the highest rates for both cancers despite its lack of the oil and coal required for chemical and manufacturing industries and its dependence on dairy and agricultural products for income. The incidence of the other major cancers also varies greatly from one nation to the next, but not in the way most of us must have been led to believe from reading the many news reports about newly discovered carcinogens in our environment.
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From page 24... ...
For example, it is possible to estimate accurately the extent to which time spent indoors in cold climates increases our exposure to the background radiation that emanates from many building materials, and to speculate that this increased exposure might account for some of the extra incidence of cancer in the northeastern United States. Similarly, it is easy to measure exposures to infectious agents.
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From page 25... ...
Judging from the observed differences in cancer rates among populations with different diets, it is highly likely that the United States will eventually have the option of adopting a diet that reduces its incidence of cancer by approximately one-third, and it is absolutely certain that another third could be prevented by abolishing smoking. Those reductions would be roughly equivalent to the reduction in mortality from the infectious diseases brought about by improved hygiene and better health care delivery during the 19th century.
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From page 26... ...
The main exceptions to this rule occur when some dietary restriction leads to a deficiency disease involving some particular tissue, thereby raising the incidence of cancer in that tissue. For example, deficiency of methyl donors such as choline leads to liver damage and raises the incidence of spontaneous liver cancer in rats.
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From page 27... ...
that affect cell differentiation and provoke cell proliferation. These agents appear to act primarily on processes occurring in cell membranes, including the responses to certain 2-11
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From page 28... ...
Whenever dietary experiments discriminate between the early and late stages of carcinogenesis, they usually show that the late stages are most affected by changes in the diet. The mechanisms underlying such effects are not known, but it is clear that normal dietary components can either raise or lower the incidence of cancers that have been initiated by exposing animals to carcinogens in the diet or by other routes.
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From page 29... ...
Cold Spring Harbor laboratory, Cold Spring Harbor, N.Y. 3 volumes, 1,889 pp.
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