Interim results from the first large-scale randomized clinical trial testing an intervention to reduce dietary fat intake as part of postsurgical breast cancer management have shown that women who reduce their consumption of fat after treatment for early-stage breast cancer may also reduce their risk of recurrence.

Between 1994 and 2001, WINS investigators recruited 2,437 women with invasive breast cancer who were between the ages of 48 and 79 at the time of enrollment into the study. At the start of the study, both groups consumed similar amounts of calories from fat. At the end of the first year of observation, the women in the dietary intervention group had reduced their fat intake by an average of 23 grams per day compared with only a 5-gram-per-day drop in the control group.

The difference between the two groups was maintained throughout the trial. By the fifth year of the trial, the women in the intervention group weighed an average of 6 pounds less than the women in the control group. After a median of 5 years of follow-up, breast cancer had recurred in 9.8 percent of the women on the low-fat diet and 12.4 percent of those on the standard diet. This amounted to a 24-percent reduction in the relative risk of recurrence for the women on the low-fat diet.

The authors acknowledge several limitations to their study, including the possibility that weight loss in the intervention group or other dietary factors may have influenced the outcome. However, stated lead author Dr. Rowan Chlebowski of the Los Angeles Biomedical Research Institute in an accompanying press release, "Although further confirmation is needed…these results suggest that an intervention aimed at reducing dietary fat consumption can reduce the risk of breast cancer recurrence."