Has the concern about breast cancer gone too far, prompting many women to neglect far more serious risks to their health and life? Two 1997 polls certainly suggest that. A New York Times/CBS News Poll found that 52 percent of women think that they are more likely to die of breast cancer than heart disease. And a survey of 1,000 women 30 to 80 years old by Merck Media Minutes, a newsletter from Merck & Co., reported that women ranked breast cancer as the leading risk to their health, above heart disease and lung cancer. But the facts say otherwise.
Heart disease is responsible for 30 Percent of the deaths among American women. Breast cancer accounts for only 3 percent. And breast cancer is not even the leading killer among the cancers that strike American women. Lung cancer causes many more deaths among women, yet it does not come close to breast cancer when women are asked about their health concerns. The Merck survey showed that five times as many women listed breast cancer rather than lung cancer as the health topic that interested them the most.
Of course, lung cancer rarely strikes before age 50, even among women who have been lifelong heavy smokers. Heart disease, too, is unlikely to kill women younger than 60, while breast cancer does sometimes strike women in their 30s and 40s. But premenopausal breast cancer is not nearly so common as most women seem to believe.
Breast cancer is primarily a disease of older women. By age 35, a woman has 1 chance in 622 of developing breast cancer. The risk rises to 1 in 93 by age 45, 1 in 33 by age 55 and 1 in 17 by age 65. The "one woman in eight" figure now frequently heard refers to the lifetime risk of breast cancer for a woman who lives beyond the age of 85. And while the incidence of breast cancer rose during the 1980s, it has leveled off in recent years, suggesting that the "epidemic," if there was one, has begun to wane.
Furthermore, breast cancer is not nearly so deadly as many women think. The death rate has been dropping lately, thanks largely to earlier detection and improved treatments. The five-year survival rate for women with localized breast cancer is now 97 percent (up from 72 percent in the 1940s). Even if the cancer has spread to tissues surrounding the breast, 76 percent of the women will be alive five years later. Over all, including cases diagnosed in an advanced stage, 65 percent of women with breast cancer will survive for 10 years and 56 percent for 15 years.
But don't think I am callous about this disease. It took three of my friends in their early 40s, and two of them left behind young children. But a dozen other friends who had breast cancer are alive and well many years -- for some, decades -- after their cancers were discovered.
WHO IS AT RISK?
Women are very confused about the factors that can influence their risk of developing breast cancer. Many worry unduly because there is breast cancer in their families. It is only cancer in first-degree relatives -- a mother, sister or daughter -- that might raise a woman's risk above that of the general population. Only 10 percent to 15 percent of breast cancers are familial, and not all of those are hereditary. Common environmental factors might also play a role. Now that researchers know which genes are responsible for hereditary breast cancer, a woman who can afford genetic testing can find out if she is indeed at increased risk.
As for the 85 percent of cases without a family history, there are several well-established risk factors, and some are amenable to adjustment. The primary risk factor is aging, something we are all stuck with. The risk also increases if menarche comes at an early age or menopause starts late -- both lengthen the exposure of breast tissue to high doses of growth-stimulating estrogens. A woman who started to menstruate before age 14 has a risk that is 30 percent higher than a woman who reached menarche at 16. Because of improved nutrition, better control of childhood infections and reduced physical activity among girls, the average age of menarche has dropped to less than 13 from 16 in the last 130 years. Likewise, a woman who enters menopause at age 55 or later has a risk 50 percent higher than that for a woman whose menopause begins earlier.
Another risk factor is having a first baby late in life or having no biological children, which one study suggests could account for almost 30 percent of the breast cancer cases in this country. A pregnancy carried to term changes breast cells in a way that helps block abnormal growth later. Having a first child at age 30 or later, or having no children, nearly doubles the risk of breast cancer, compared with the risk faced by a woman who bears her first child before she is 20. Furthermore, the earlier a woman has a child, the more children she is likely to have, and these additional pregnancies further protect her breasts, as does prolonged breast feeding.
REDUCING THE RISK
Women do not always have a choice about when -- or if -- they give birth and nurse babies. But there are other factors that can raise the risk of breast cancer over which women do have control. According to Dr. Graham A. Colditz and Dr. A. Lindsay Frazier of Harvard Medical School, preventive efforts should be focused on girls because it is young breasts that are most vulnerable to the molecular damage that can accumulate over the years.
Two habits that often start in the teen-age years are especially dangerous: alcohol consumption and cigarette smoking. The Nurses' Health Study, based at Harvard, found that compared with nondrinkers, women who consumed more than one drink a day faced a 2 1/2-fold increase in breast cancer risk. Other studies have indicated that this risk is limited almost entirely to women who start drinking before age 25.
As for smoking, a large Danish study found a 60 percent increase in the risk of breast cancer among women who had smoked cigarettes for more than 30 years. Smokers also tended to develop cancer at younger ages than nonsmokers. The Harvard researchers noted that among women who smoked more than 25 cigarettes a day, those who had started to smoke before they were 16 faced an 80 percent increase in breast cancer risk.
On the other hand, vigorous physical activity in adolescence and young adulthood is protective, perhaps because it can delay menarche and, like pregnancy, reduce the number of ovulatory menstrual cycles. But even after menopause, exercise is likely to be helpful because it reduces body fat, where estrogens are formed from other steroids. As you might guess,weight gain in adulthood increases the postmenopausal breast cancer risk. As for diet, women would be wise to eat more fiber and less fat. Women on high-fat diets have higher levels of estrogen in their blood, which can spur the growth of breast cancer. However, in a new study of premenopausal women by Dr. David Rose of the American Health Foundation, wheat bran -- one cup or two servings of a whole-bran cereal daily -- diminished blood levels of estrogen. Studies at Tufts University have indicated that dietary fiber from vegetables and fruits,legumes and cereal brans can lower the risk of breast cancer.
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Copyright © 1997 Steven J. Milloy. All rights reserved. Site developed and hosted by WestLake Solutions, Inc.