Final Word on Diet-Breast Cancer Link Must Come From Clinical Trials: WHI

Oncology NEWS International Vol 5 No 3, Volume 5, Issue 3

BETHESDA, Md--Concerned that a New England Journal of Medicine article reporting no link between fat intake and breast cancer might deter women from joining the diet-cancer segment of the NIH-sponsored Women's Health Initiative (WHI), its top leaders took an unusual step.

BETHESDA, Md--Concerned that a New England Journal of Medicinearticle reporting no link between fat intake and breast cancermight deter women from joining the diet-cancer segment of theNIH-sponsored Women's Health Initiative (WHI), its top leaderstook an unusual step.

They issued a press statement that challenges, not the article'sfindings, but the notion that the question of whether dietaryfat contributes to the development of breast cancer can be answeredoutside of a randomized clinical trial.

"Numerous other studies . . . support such a link,"the statement said. "The WHI trial is designed to answerconfidently this and other important questions related to women'shealth."

The article, which appeared in the February 8, 1996, issue ofthe Journal and garnered extensive media attention, detailed areanalysis of seven cohort studies that had investigated the linkbetween fat and breast cancer. The studies involved a total of337,819 women.

"We found no evidence of a positive association between totaldietary fat intake and the risk of breast cancer," said leadauthor David J. Hunter of the Harvard School of Public Health."There was no reduction in risk even among women whose energyintake from fat was less than 20% of total energy intake."

The article noted, and the WHI statement emphasized, that othertypes of studies have reached contrary conclusions. These includeepidemiologic studies, comparisons of women living in one countrywith those from that country who have migrated to another andchanged their diet, case-control studies, and animal feeding trials.

This leads to the possibility that the new findings might resultfrom some defect within cohort studies themselves, the WHI statementsaid. In cohort studies, the amount of fat is estimated priorto the development of a breast tumor; in case-control studies,the estimate comes after the cancer appears. Cohort studies generallyget the nod over case-control studies as the more reliable. However,"neither of these types of studies is as reliable as a clinicaltrial," the WHI said.

In an interview with Oncology News International, WHI directorDr. Loretta Finnegan and Dr. Jacques Rossouw, WHI's lead projectofficer, acknowledged their concern that women who heard aboutthe conclusions of the cohort reanalysis might refuse to joinWHI's study.

"Women might be advised by their physicians that it's notworth participating in the trial because it's not likely to succeed,"Dr. Rossouw said. "We don't agree. We think there is a reasonablystrong hypothesis that changing the diet will lower cancer risks."

Dr. Finnegan emphasized that the final word on the subject shouldbe based on "what we call the gold standard, which is theclinical trial, which is the WHI trial."

More than 16,000 women, aged 50 to 79, have enrolled in the dietarycomponent of the WHI at 40 clinical centers nationwide; officialshope that 48,000 will sign up before enrollment ends early in1998. The women will be followed for 9 years.

"What we're testing is whether a total dietary pattern, whichincludes reduction in dietary fats but also increases in fruits,vegetables, and grains, has health benefits for preventing breastcancer, colorectal cancer, and heart disease," Dr. Rossouwsaid.

Women can obtain information on participating in the WHI dietarystudy by calling 1-800-54-WOMEN.