6 Factors Which Raise Breast Cancer Risk

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