Over the past 20 years since the signing of the National Cancer Act, the largest gains in the “war on cancer” have been in cancer prevention, American Cancer Society President Walter Lawrence told a meeting of science writers last week.

While tremendous gains have been made in treatment of childhood leukemia, other childhood cancers, testicular cancers, and breast cancer, there has been modest progress in treatment results for all sites of cancer, Lawrence said. “Clearly, we are far from being able to declare victory in this campaign . My own view is that our biggest gain in this arena is our increased appreciation of, and focus on, cancer prevention strategies,” Lawrence said.

His remarks were made at the ACS Science Writers’ Seminar in St. Petersburg, FL, last week. Lawrence later told The Cancer Letter that he intends to increase attention on cancer prevention and control this year. Lawrence, emeritus director of the Massey Cancer Center at the Medical College of Virginia, also is a member of the National Cancer Advisory Board.

ACS supports an increasing amount of prevention research, including new clinical trials of diet and chemoprevention.

“Basic research in the area of causation, particularly the identification of various cellular gene alterations, is moving at a rapid pace,” Lawrence said . “This knowledge will aid us in developing prevention strategies in the future and will also very soon allow identification of high risk subpopulations among us” who would be candidates for aggressive screening and early detection methods, or involvement in chemoprevention clinical trials.

Increasing Breast Cancer incidence

Offsetting gains in early diagnosis of breast cancer is the increasing incidence of the disease, Lawrence said.

“The report we made to the nation in early 1991– that the lifetime risk of breast cancer for women had increased to one in nine–was not meant to be a scare tactic, but a means of pointing out the urgency of early detection of breast cancer,” Lawrence said, referring to a recent article in “The New York Times” critical of the Society’s report .

“These figures are certainly accurate when one considers a life expectancy of 85 years and that the major escalation of this risk occurs in the older citizen age range,” Lawrence said . “Although we have incomplete information on the cause of this increasing risk, the increasing mean age of our population must be considered a major factor . It is our view that awareness of this one in nine estimate by women is important rather than frightening. It helps us break down barriers that prevent women from availing themselves of life-saving mammograms .”

On the issue of silicone gel breast implants, ACS has urged continued research on the safety of the devices, but recommended that FDA allow the implants to remain available to women who have had a mastectomy, Lawrence said.

ACS is supporting two major cancer prevention studies . The first, led by Daniel Nixon, ACS vice president for professional education, will test the hypothesis that added wheat fiber in a controlled dietary study will reduce the recurrence rate of colon polyps in patients who have had colon polyps removed. The pilot project, a randomized, controlled, doubleblind clinical trial, is being conducted in Virginia.

The treatment agent is a wheat fiber supplement which will allow an intake of 32-35 grams of dietary fiber per day. All study subjects will be encouraged to follow ACS dietary guidelines. Both groups will be followed with colonoscopy for recurrence of polyps, one and three years following the original removal of polyps, or annually if their first follow-up exam reveals new polyps.

The intervention group will receive fiber cereal packets each containing 20 grams of fiber. Controls will get a placebo cereal packet. The pilot phase will take about two years, and if successful, the full implementation phase will begin, and will take about four years.

The second project, also led by Nixon, will study the prevention of breast cancer recurrence through control of dietary fat and weight management. Subjects on adjuvant breast cancer chemotherapy will be randomized to a calorie controlled, low fat diet.

The feasibility study will enroll 180 postmenopausal breast cancer patients in one ACS division, and take about one and a half years. The second phase of the study will involve 1,800 patients and take approximately five years.

“The concepts being examined by these two pilot studies are not really new, but these trials should tell us whether such dietary interventions are both realistic and feasible,” Lawrence said.

The ACS projects will use trained volunteers to assist in dietary counseling, data management, and patient follow-up. Cost of both projects is estimated at $400,000 per year with the use of volunteers . Nixon estimated the studies would cost more than $1 million per year without volunteers .