© The Author 2007. Published by Oxford University Press.
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Response: Re: Dietary Fat Reduction and Breast Cancer Outcome: Interim Efficacy Results From the Women's Intervention Nutrition Study
Affiliations of authors: Department of Medicine, Los Angeles Biomedical Research Institute at Harbor–University of California, Los Angeles Medical Center, Torrance, CA (RTC); Department of Nutrition, Beth Israel Deaconess Hospital, Boston, MA (GLB)
Correspondence to: Rowan T. Chlebowski, MD, PhD, Los Angeles Biomedical Research Institute at Harbor–University of California, Los Angeles Medical Center, 1124 W. Carson St, Bldg J-3, Torrance, CA 90502 (e-mail: rchlebowski{at}gmail.com).
We agree with Altundag and Kurt that estrogen receptor (ER)–negative breast cancers are more likely to recur early and that longer follow-up could alter the differential dietary effect we observed. However, after an average follow-up of more than 8 years, the Women's Health Initiative trial evaluating the influence of a similar dietary change on breast cancer incidence also saw evidence of effect in hormone receptor–negative cancers (1). In a recent update of the Women's Intervention Nutrition Study (2), we continued to see the largest effect on relapse-free survival in the ER- and progesterone receptor–negative subgroup (hazard ratio of 0.46, 95% confidence interval = 0.26 to 0.80) for relapse–free survival influence of dietary modification versus control group randomization. By protocol design, definitive analyses addressing this issue with 3 years of follow-up after completion of recruitment will be available later this year (3).
We agree with Pierce et al. that maintaining a lifestyle intervention is difficult but suggest, based on our experience (1–3), that it will be difficult to achieve greater adherence in any clinical trial setting. Finally, it is extremely unlikely that a 5% difference in recent contact between groups could explain our results, because such an explanation assumes that all those not contacted had relapsed. In addition, in the hormone receptor–negative subgroup, early rather than late separation for relapse-free survival events was seen and such early events would not be influenced by a small difference in the proportion of participants with contacts late in the follow-up period.
REFERENCES
(1) Prentice RL, Caan B, Chlebowski RT, Patterson R, Kuller LH, Ockene JK, et al. Low-fat dietary pattern and risk of invasive breast cancer. The Women's Health Initiative randomized controlled dietary modification trial. JAMA (2006) 295:629–42.
(2) Chlebowski RT, Blackburn GL, Elashoff RM, Hoy KM, Thomson CA, Nixon DW, et al. Mature analysis from the Women's Intervention Nutrition Study (WINS) evaluating dietary fat reduction and breast cancer outcome. Breast Cancer Res Treat (2006) 100(Suppl1):S16.
(3) Chlebowski RT, Blackburn G, Thomson CA, Nixon DW, Shapiro A, Hoy MK, et al. Dietary fat reduction and breast cancer outcome: interim efficacy results from the Women's Intervention Nutrition Study (WINS). J Natl Cancer Inst (2006) 98:1767–76.
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J Natl Cancer Inst 2007 99: 899-900.
J Natl Cancer Inst 2007 99: 900.
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