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Cancer Epidemiol Biomarkers Prev. 2014 Dec;23(12):2924-35. doi: 10.1158/1055-9965.EPI-14-0922. Epub 2014 Sep 25.

Cancer incidence and mortality during the intervention and postintervention periods of the Women's Health Initiative dietary modification trial.

Author information

1
Health Promotion Sciences, Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson, Arizona. cthomson@email.arizona.edu.
2
Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
3
Kaiser Permanente, Northern California, Oakland, California.
4
Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington.
5
Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance, California.
6
Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts.
7
Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York.
8
Department of Epidemiology, School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania.
9
Department of Preventive Medicine, Stony Brook University School of Medicine, Stony Brook, New York.
10
Department of Preventive Medicine, University of Tennessee Health Sciences Center, Memphis, Tennessee.
11
Department of Epidemiology and Prevention, Wake Forest School of Medicine, Winston-Salem, North Carolina.

Abstract

BACKGROUND:

The Women's Health Initiative (WHI) low-fat (20% kcal) dietary modification (DM) trial (1993-2005) demonstrated a nonsignificant reduction in breast cancer, a nominally significant reduction in ovarian cancer, and no effect on other cancers (mean 8.3 years intervention). Consent to nonintervention follow-up was 83% (n = 37,858). This analysis was designed to assess postintervention cancer risk in women randomized to the low-fat diet (40%) versus usual diet comparison (60%).

METHODS:

Randomized, controlled low-fat diet intervention for prevention of breast and colorectal cancers conducted in 48,835 postmenopausal U.S. women, ages 50 to 79 years at 40 U.S. sites. Outcomes included total invasive cancer, breast cancer, and colorectal cancer, and cancer-specific and overall mortality.

RESULTS:

There were no intervention effects on invasive breast or colorectal cancer, other cancers, or cancer-specific or overall mortality during the postintervention period or the combined intervention and follow-up periods. For invasive breast cancer, the hazard ratios (HR) and 95% confidence interval (CI) were 0.92 (0.84-1.01) during intervention, 1.08 (0.94-1.24) during the postintervention period, and 0.97 (0.89-1.05) during cumulative follow-up. A reduced risk for estrogen receptor positive/progesterone receptor-negative tumors was demonstrated during follow-up. In women with higher baseline fat intake (quartile), point estimates of breast cancer risk were HR, 0.76 (95% CI, 0.62-0.92) during intervention versus HR, 1.11 (95% CI, 0.84-1.4) during postintervention follow-up (Pdiff = 0.03).

CONCLUSIONS:

Dietary fat intake increased postintervention in intervention women; no long-term reduction in cancer risk or mortality was shown in the WHI DM trial.

IMPACT:

Dietary advisement to reduce fat for cancer prevention after menopause generally was not supported by the WHI DM trial.

PMID:
25258014
PMCID:
PMC4257879
DOI:
10.1158/1055-9965.EPI-14-0922
[Indexed for MEDLINE]
Free PMC Article

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