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.
They issued a press statement that challenges, not the article's findings, but the notion that the question of whether dietary fat contributes to the development of breast cancer can be answered outside of a randomized clinical trial.
"Numerous other studies . . . support such a link," the statement said. "The WHI trial is designed to answer confidently this and other important questions related to women's health."
The article, which appeared in the February 8, 1996, issue of the Journal and garnered extensive media attention, detailed a reanalysis of seven cohort studies that had investigated the link between fat and breast cancer. The studies involved a total of 337,819 women.
"We found no evidence of a positive association between total dietary fat intake and the risk of breast cancer," said lead author David J. Hunter of the Harvard School of Public Health. "There was no reduction in risk even among women whose energy intake from fat was less than 20% of total energy intake."
The article noted, and the WHI statement emphasized, that other types of studies have reached contrary conclusions. These include epidemiologic studies, comparisons of women living in one country with those from that country who have migrated to another and changed their diet, case-control studies, and animal feeding trials.
This leads to the possibility that the new findings might result from some defect within cohort studies themselves, the WHI statement said. In cohort studies, the amount of fat is estimated prior to the development of a breast tumor; in case-control studies, the estimate comes after the cancer appears. Cohort studies generally get the nod over case-control studies as the more reliable. However, "neither of these types of studies is as reliable as a clinical trial," the WHI said.