Information on Cancer Prevention Is Not Reaching Women
Only one in five women is aware of the role of dietary factors in breast cancer, and this dismal figure is improving only very slowly, according to a new study by PCRM’s Neal D. Barnard, M.D., and Andrew Nicholson, M.D. The study, published in Preventive Medicine, was based on telephone surveys by Opinion Research Corporation in 1991 and 1995.
When asked, “What steps, if any, are you aware of that women can take to lower their chances of developing breast cancer?” only 20 percent of women cited dietary factors as playing any role in 1991. Four years later, the figure had risen to 23 percent, a difference that is not statistically significant. In contrast, self-examination and mammography were cited as “preventive” steps by 55 percent and 37 percent, respectively, of women in 1995, in spite of the fact that neither one prevents cancer, but rather simply detects existing cancers.
Awareness of the role of diet in breast cancer was particularly low in women younger than 25, above age 64, or in lower socioeconomic groups. Only 11 percent of those with incomes below $15,000 and 3 percent of those with less than a high school education were aware of the diet-cancer connection.
Additional questions were asked with more prompting to see whether the numbers improved. When subjects were asked to consider dietary steps specifically, rather than mammograms or any other factor, the number citing reducing intake of fat or meat, or increasing intake of vegetables, fruit, fiber, or vegetarian meals increased to 37 percent in 1991 and to 52 percent in 1995. This increase is significant, although these figures still pale in comparison with the number of Americans who are aware of the links between diet and heart disease.
When subjects were asked a yes-or-no question as to whether they had ever heard that low-fat diets might reduce the risk of breast cancer, 58 percent of subjects said “yes” in the 1995 survey. Again, differences in response rates by age, race, income, and education were apparent.
Countries where fattier diets are consumed have much higher breast cancer rates, presumably because fat in foods increases the amount of estrogen in the blood. Fiber reduces estrogen levels. Federal cancer authorities hold that the evidence linking diet and breast cancer is strong and publish limited informational materials for the public. However, mammography and self-examination have been much more aggressively promoted by governmental agencies and private groups.
The survey did not address the possibility that some women were aware of theories linking diet and breast cancer but did not believe the evidence. A large study of nurses conducted by Harvard University, for example, failed to detect any relationship between dietary fat and breast cancer, a result that has been attributed to the fact that the subjects in that study did not vary greatly in their dietary habits. International comparisons and case-control studies show an important role for diet in breast cancer.
Other studies have shown that knowledge about cancer prevention is far from universal. The 1987 National Health Interview Survey asked subjects to name diseases that might be related to what people eat and drink. Less than half (48 percent) mentioned cancer of any type. A surprising 70 percent thought their diets were already healthful and there was no reason to change. A separate survey, conducted in 1991, found that 60 percent of respondents were confident that they already knew how to choose healthy foods. Yet only 8 percent thought that five or more daily servings of fruits and vegetables were needed for good health, and only 40 percent thought that eating fruits and vegetables would help prevent cancer.