Cancer Prevention Strategies Involve Individuals and Society

ARLINGTON, Va—There are certainly things we can do individually to avoid getting cancer, yet other preventive measures must be taken by society at large, Devra Lee Davis, PhD, of the World Resources Institute, Washington, said at the Second Comprehensive Cancer Care Conference. The meeting was sponsored by the University of Texas Houston Medical School and the Center for Mind-Body Medicine, in collaboration with the NCI and the National Center for Complementary and Alternative Medicine.

What Individuals Can Do

“There are a number of things women can do as individuals that may help them avoid breast cancer,” Dr. Davis said. Eating soy, fish, olive oil, and certain vegetables may help, perhaps by reducing the level of estrogen in a woman’s body, she said. Vigorous exercise can also reduce the levels of circulating estrogen.

Avoiding cigarette smoking is another individual preventive step. “The earlier in life a young girl smokes, the greater her risk of breast cancer,” Dr. Davis noted. Alcohol is still another predisposing factor to breast cancer, especially in woman taking estrogen replacement therapy.

“Other breast cancer preventives, in contrast, must be undertaken by society if they are to be effective,” she said. An example is how Americans as a whole have dealt with the pesticide DDT, which has been shown in the laboratory to increase the growth of breast cancer cells. In a European study of 1,000 women, she said, those with breast cancer had higher blood levels of DDT than did controls, likewise suggesting a causative relationship between DDT and breast cancer.

Wildlife Studies

Wildlife studies suggest a link between DDT and higher estrogen levels. A lake in Florida was found to contain DDT, and alligators in this lake had four times more female hormones in their bodies than alligators elsewhere. What’s more, the male alligators had very small penises, probably caused by the feminizing effect of the excess female hormones.

Fortunately, DDT use in the United States was banned in 1973. “And as a result, the level of DDT in Americans’ blood today is 10 times lower than during the 1970s,” Dr. Davis said. “It also looks as if US breast cancer rates are no longer increasing,” she said, suggesting that there could be a link between the leveling off of breast cancer incidence and the drop in DDT blood levels.

There may be other potential environmental sources of cancer risk, Dr. Davis warned. Certain plastics and fuels may be involved, but they are hard to study because they do not remain long in the body. When Red Dye No. 3, which is present in some processed foods, is placed in the presence of breast cancer cells, the cells increase. “This is very important evidence that we should not be exposing ourselves to this compound,” she said.

Dealing with such environmental cancer risks is the job not just of federal agencies like the FDA, but of all Americans, Dr. Davis contends. For instance, while she would like to see the FDA take Red Dye No. 3 out of processed foods, she would like even more for Americans to keep such foods out of schools. “The only way you can change public policy is through a group of concerned citizens,” she asserted.

Americans in their efforts to avoid cancer, either individually or as a society, need more input from cancer scientists to help them make good decisions about lifestyle and the environment. “Some cutting edge cancer prevention research is underway that may help,” said Carolyn Aldige, president, Cancer Research Foundation of America.

The Foundation, in its 14 years of existence, has invested $32 million in such research as well as in cancer prevention education. A large part of its support goes to researchers doing small breakthrough studies. When the results show promise, the studies are then expanded by the National Cancer Institute, she said.

Some of the research the Foundation is currently supporting includes:

A University of Nebraska study to see whether selenium can protect against prostate cancer.

A University of North Carolina investigation to determine whether folate, which is found in leafy vegetables and cereals, can prevent cancer.

An Oregon Health Sciences University inquiry to test whether vitamin D can prevent prostate cancer.

A University of Virginia clinical trial to test a melanoma vaccine.

A study to learn whether retinoids, delivered via a spray into the lungs, might protect against lung cancer.

Clement Bezold, PhD, a political scientist and president of the Institute for Alternative Futures, Alexandria, Virginia, said that “Americans will undoubtedly receive still more help from cancer scientists in devising cancer prevention strategies during the next few years.”

For instance, in the area where prevention and early detection meet, Dr. Bezold anticipates that cancer researchers will identify many more molecular markers to identify early cancers or precancerous conditions.

The Goal for 2015

“The American Cancer Society wants to decrease the incidence of cancer in the United States by 25% by the year 2015,” Dr. Bezold said. He believes that this goal is realistic because he thinks new cancer preventives will be developed over the next decade and more information will be available about nutrition and cancer.

The question, of course, he said, is what Americans individually and collectively will do with these preventives. “It is really their ultimate actions, or lack thereof, that will determine whether the US cancer incidence plummets in the next millennium,” he said.