Low-Fat Dietary Pattern and Breast Cancer Mortality in the Women’s Health Initiative Randomized Controlled Trial

• Main Authors: Chlebowski, Rowan T., Aragaki, Aaron K., Anderson, Garnet L., Thomson, Cynthia A., Manson, JoAnn E., Simon, Michael S., Howard, Barbara V., Rohan, Thomas E., Snetselar, Linda, Lane, Dorothy, Barrington, Wendy, Vitolins, Mara Z., Womack, Catherine, Qi, Lihong, Hou, Lifang, Thomas, Fridtjof, Prentice, Ross L.
• Other Authors: Univ Arizona, Canc Ctr
• Language: en
• Published: AMER SOC CLINICAL ONCOLOGY 2017
• Online Access: http://hdl.handle.net/10150/625754; http://arizona.openrepository.com/arizona/handle/10150/625754

Purpose Earlier Women's Health Initiative Dietary Modification trial findings suggested that a low-fat eating pattern may reduce breast cancers with greater mortality. Therefore, as a primary outcome-related analysis from a randomized prevention trial, 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. Patients and Methods The trial randomly assigned 48,835 postmenopausal women with normal mammograms and without prior breast cancer from 1993 to 1998 at 40 US clinical centers to a dietary intervention with goals of a reduction of fat intake to 20% of energy and an increased intake of fruits, vegetables, and grains (40%; n = 19,541) or to a usual diet comparison (60%; n = 29,294). Results In the dietary group, fat intake and body weight decreased (all P < .001). During the 8.5-year dietary intervention, with 1,764 incident breast cancers, fewer deaths occurred as a result of breast cancer in the dietary group, which was not statistically significant (27 deaths [0.016% per year] v 61 deaths [0.024% per year]; hazard ratio [HR], 0.67; 95% CI, 0.43 to 1.06; P = .08). During the same period, deaths after breast cancer (n = 134) were significantly reduced (40 deaths [0.025% per year] v 94 deaths [0.038% per year]; HR, 0.65; 95% CI, 0.45 to 0.94; P = .02) by the dietary intervention. During the 16.1-year follow-up, with 3,030 incident breast cancers, deaths after breast cancer also were significantly reduced (234 deaths [0.085% per year] v 443 deaths [0.11% per year]; HR, 0.82; 95% CI, 0.70 to 0.96; P = .01) in the dietary group. Conclusion Compared with a usual diet comparison group, a low-fat dietary pattern led to a lower incidence of deaths after breast cancer. (C) 2017 by American Society of Clinical Oncology