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Factors
Which Increase Your Risk of Cancer
There are a number of factors, apart from diet which affect your
risk of cancer.
Hormones: Oral contraceptives
appear to increase risk. Although newer birth control pills contain
less estrogen and progesterone than older versions, evidence
suggests some increase in risk from oral contraceptives. The same
may be true of supplemental hormones given to women after menopause.
In both cases, it makes sense for women to discuss the risks and
benefits with their personal physicians.
Overweight: Higher body weight
increases the risk of breast cancer after menopause. Before
menopause, weight does not increase risk.
Radiation: Of all the different
parts of the body, the breast is probably the most sensitive to
X-ray damage, and there is no doubt that X-rays to the breast can
cause cancer. This raises obvious concerns about mammograms, which,
after all, are X-rays. Annual mammograms are clearly beneficial for
women over 50. But women should schedule mammograms only at modern
facilities which do them regularly and maintain new equipment,
keeping radiation doses to a minimum.
Below age 50, scientific studies do not show any clear benefit from
routine mammograms. The reason is that many cancers are missed on
mammograms, and women have sometimes been falsely reassured by a
negative mammogram, leading to delays in diagnosis and treatment.
Before age 50, routine mammograms do not improve on the power of
physical (and self) examination.
Genetics: About 5 percent of
breast cancer cases are purely attributable to genetics. In such
cases, cancer is passed from parent to child as a dominant trait,
and the family tree is riddled with the disease. And for a larger
group of individuals, genetics probably makes a contribution in
subtle ways. For example, it may well be that different genes
influence one's susceptibility to carcinogens, the strength of the
immune system, body weight, and other factors. Each of these is also
influenced by diet.
Toxic Chemicals: Locations near
toxic waste sites tend to have higher than average rates of breast
cancer. That is true for other forms of cancer, too. And you don't
have to live near a chemical waste site to be concerned about toxic
exposures. Toxic chemicals are available at any grocery store in the
form of pesticides. Fortunately, organic produce is now more widely
available. Chemical contaminants also end up in meats, because
pesticides are sprayed on grains that are fed to cows, chickens,
pigs, and other livestock. In storage bins, feed grains are sprayed
again. Animals concentrate these chemicals in their tissues.
Women who avoid eating animal products have much smaller
concentrations of pesticides in their breast milk. Levels of the
pesticides DDT, chlordane, hepatochlor, dieldrin, and PCBs have been
measured at markedly lower levels in vegetarians than those of
omnivores. In a 1981 study, vegetarians had only 1 to 2 percent of
the national average levels of certain pesticides and industrial
chemicals compared to that of average Americans. The exception was
polychlorinated biphenyls (PCBs), for which the vegetarians had
levels that were comparable to meat-eaters. PCBs in the body often
reflect past fish consumption, and levels drop slowly after people
adopt a vegetarian diet. Once PCBs are in the body tissues, avoiding
contaminated fish will reduce PCB levels only very slowly.
Time between Puberty and First Pregnancy:
The younger a girl is when puberty occurs, the higher her risk of
breast cancer. Also, the later the age of her first pregnancy, the
higher her risk. It may be that the early age of puberty simply
indicates elevated hormone levels, as was described above. As
high-fat, low-fiber diets have spread from the wealthy part of the
population to, now, the entire population, the age of puberty has
dropped dramatically from age 17 in 1840 to 12.5 today. Similarly,
as Japan's diet has westernized since World War II, the age of
puberty has dropped from 15 to 12.5. It may be that early puberty
and cancer are both the result of a hormonal aberration.
The time period between puberty and the first pregnancy is one in
which the body may be particularly sensitive to carcinogens, and the
longer this time period is, the greater the risk.
Source: Physicians Committee for Responsible Medicine
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