Low-fat diet leads to lower death rates after breast cancer

Women who ate a low-fat diet had a lower incidence of death after breast cancer, according to a study published in Journal of Clinical Oncology.

However, researchers reported that the low-fat diet did not significantly reduce deaths.

“Earlier Women’s Health Initiative Dietary Modification trial findings suggests that a low-fat eating pattern may reduce breast cancers with greater mortality,” Rowan T. Chlebowski MD, PhD, of the City of Hope National Medical Center in California, and colleagues wrote. “We examined the long-term influence of this intervention on deaths as a result of and after breast cancer during 8.5 years (median) of dietary intervention and cumulatively for all breast cancers diagnosed during 16.1 years (median) of follow-up.”

The researchers conducted a randomized controlled trial of 48,835 women from 40 clinical centers in the United States. All women had normal mammograms and no history of breast cancer from 1993 to 1998. The researchers randomly assigned women to either a diet with a reduced fat intake and increased fruit, vegetable and grain intake (40%; n = 19,541) or a usual diet (60%; n = 29, 294).

Women in the low-fat diet group experienced lower fat intake and lost weight (P < .001). A total of 1,764 incident breast cancers occurred during the intervention period. Deaths as a result of breast cancer occurred in 27 women (0.016% per year) in the low-fat diet group compared with 61 women (0.024% per year) in the usual diet group (HR = 0.67; 95% CI, 0.43-1.06); Chlebowski and colleagues found this “not statistically significant.”

One hundred thirty-four patients died after breast cancer during the intervention period. The low-fat diet group experienced significantly reduced deaths (40 [0.025% per year] vs. 94 [0.038% per year]; HR = 0.65; 95% CI, 0.45-0.94; P = .02).

A total of 3,030 breast cancers occurred during the 16.1-year follow-up period. Again, deaths after breast cancer appeared significantly reduced in the dietary intervention group (234 [0.085% per year] vs. 443 [0.11% per year]; HR = 0.82; 95% CI, 0.7-0.96; P = .01).

Researchers acknowledged the study was limited by lack of comprehensive information on breast cancer therapies, and post hoc analyses.

“Women randomly assigned to a low-fat dietary pattern had a nonsignificantly lower risk [for] death as a result of breast cancer and a significantly reduced risk [for] death after breast cancer,” the researchers wrote. “Future studies of other lifestyle interventions on breast cancer incidence and outcome could incorporate some form of a low-dietary pattern as a base.” – by Andy Polhamus

Disclosure: Chlebowski reports consulting or advisory roles with Amgen, AstraZeneca, Genentech, Novartis and Pfizer, as well as speaking roles with Genentech and Novartis. Please see the full study for a list of all other researchers’ relevant financial disclosures.