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Low-fat dietary pattern and cancer incidence in the Women's Health Initiative Dietary Modification Randomized Controlled Trial.

ABSTRACT: BACKGROUND:The Women's Health Initiative Dietary Modification (DM) Randomized Controlled Trial evaluated the effects of a low-fat dietary pattern on chronic disease incidence, with breast cancer and colorectal cancer as primary outcomes. The trial protocol also listed ovarian cancer and endometrial cancer as outcomes that may be favorably affected by the intervention. METHODS:A total of 48,835 postmenopausal women were randomly assigned during 1993-1998 to a DM intervention (n = 19,541) or comparison (usual diet; n = 29,294) group and followed up for an average of 8.1 years. The intervention goal was to reduce total fat intake to 20% of energy and to increase consumption of vegetables, fruits, and grains. Cancer outcomes were verified by pathology report review. We used weighted log-rank tests to compare incidence of invasive cancers of the ovary and endometrium, total invasive cancer, and invasive cancers at other sites between the groups. All statistical tests were two-sided. RESULTS:Ovarian cancer risk was lower in the intervention than in the comparison group (P = .03). Although the overall ovarian cancer hazard ratio (HR) was not statistically significantly less than 1.0, the hazard ratio decreased with increasing intervention duration (P(trend) = .01). For the first 4 years, the risk for ovarian cancer was similar in the intervention and control groups (0.52 cases per 1000 person-years in the intervention group versus 0.45 per 1000 person-years in the comparison group; HR = 1.16, 95% confidence interval [CI] = 0.73 to 1.84); over the next 4.1 years, the risk was lower in the intervention group (0.38 cases per 1000 person-years in the intervention group versus 0.64 per 1000 person-years in the comparison group; HR = 0.60, 95% CI = 0.38 to 0.96). Risk of cancer of the endometrium did not differ between the groups (P = .18). The estimated risk of total invasive cancer was slightly lower in the intervention group than in the control group (HR = 0.95, 95% CI = 0.89 to 1.01; P = .10). CONCLUSIONS:A low-fat dietary pattern may reduce the incidence of ovarian cancer among postmenopausal women.

SUBMITTER: Prentice RL

PROVIDER: S-EPMC2670850 | biostudies-literature | 2007 Oct

REPOSITORIES: biostudies-literature

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Low-fat dietary pattern and cancer incidence in the Women's Health Initiative Dietary Modification Randomized Controlled Trial.

Prentice Ross L RL Thomson Cynthia A CA Caan Bette B Hubbell F Allan FA Anderson Garnet L GL Beresford Shirley A A SA Pettinger Mary M Lane Dorothy S DS Lessin Lawrence L Yasmeen Shagufta S Singh Baljinder B Khandekar Janardan J Shikany James M JM Satterfield Suzanne S Chlebowski Rowan T RT

Journal of the National Cancer Institute 20071009 20

<h4>Background</h4>The Women's Health Initiative Dietary Modification (DM) Randomized Controlled Trial evaluated the effects of a low-fat dietary pattern on chronic disease incidence, with breast cancer and colorectal cancer as primary outcomes. The trial protocol also listed ovarian cancer and endometrial cancer as outcomes that may be favorably affected by the intervention.<h4>Methods</h4>A total of 48,835 postmenopausal women were randomly assigned during 1993-1998 to a DM intervention (n = 1 ...[more]

PMID: 17925539

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Project description:BACKGROUND:Intensive dietary intervention programs may lead to benefits in vitality and other components of health quality. The Women's Health Initiative Dietary Modification (DM) intervention includes a large randomized controlled trial of an intensive intervention. OBJECTIVE:To evaluate whether the intervention is associated with improved health-related quality of life (HRQoL) subscales, overall self-reported health, depression symptoms, cognitive functioning, and sleep quality. DESIGN:This randomized controlled trial was analyzed as intent to treat. PARTICIPANTS:Between 1993 and 1998, 48,835 women aged 50 to 79 years were recruited by 40 clinical centers across the United States. Eligibility included having fat intake at baseline ?32% of total calories, and excluded women with any prior colorectal or breast cancer, recent other cancers, type 1 diabetes, or medical conditions with predicted survival <3 years. INTERVENTION:Goals were to reduce calories from fat to 20%, increase vegetables and fruit to 5+ servings, and increase grain servings to 6+ servings a day. During the first year, 18 group sessions were held, with quarterly sessions thereafter. MAIN OUTCOME MEASURES:The RAND 36-Item Health Survey was used to assess HRQoL at baseline, Year 1, and close-out (about 8 years postrandomization), and estimate differential HRQoL subscale change scores. STATISTICAL ANALYSES PERFORMED:Mean change in HRQoL scores (Year 1 minus baseline) were compared by randomization group using linear models. RESULTS:At 1 year, there was a differential change between intervention and comparison group of 1.7 units (95% CI 1.5, 2.0) in general health associated with the intervention. DM intervention improved physical functioning by 2.0 units (95% CI 1.7, 2.3), vitality by 1.9 units (95% CI 1.6, 2.2), and global quality of life by 0.09 units (95% CI 0.07, 0.12). With the exception of global quality of life, these effects were significantly modified by body mass index at baseline. CONCLUSIONS:DM intervention was associated with small, but significant improvements in three HRQoL subscales: general health, physical functioning, and vitality at 1 year follow-up, with the largest improvements seen in the women with the greatest baseline body mass index.

Project description:Background: The influence of a low-fat dietary pattern on the cardiovascular health of postmenopausal women continues to be of public health interest.Objective: This report evaluates low-fat dietary pattern influences on cardiovascular disease (CVD) incidence and mortality during the intervention and postintervention phases of the Women's Health Initiative Dietary Modification Trial.Design: Participants comprised 48,835 postmenopausal women aged 50-79 y; 40% were randomly assigned to a low-fat dietary pattern intervention (target of 20% of energy from fat), and 60% were randomly assigned to a usual diet comparison group. The 8.3-y intervention period ended in March 2005, after which >80% of surviving participants consented to additional active follow-up through September 2010; all participants were followed for mortality through 2013. Breast and colorectal cancer were the primary trial outcomes, and coronary heart disease (CHD) and overall CVD were additional designated outcomes.Results: Incidence rates for CHD and total CVD did not differ between the intervention and comparison groups in either the intervention or postintervention period. However, CHD HRs comparing these groups varied strongly with baseline CVD and hypertension status. Participants without prior CVD had an intervention period CHD HR of 0.70 (95% CI: 0.56, 0.87) or 1.04 (95% CI: 0.90, 1.19) if they were normotensive or hypertensive, respectively (P-interaction = 0.003). The CHD benefit among healthy normotensive women was partially offset by an increase in ischemic stroke risk. Corresponding HRs in the postintervention period were close to null. Participants with CVD at baseline (3.4%) had CHD HRs of 1.47 (95% CI: 1.12, 1.93) and 1.61 (95% CI: 1.02, 2.55) in the intervention and postintervention periods, respectively. However, various lines of evidence suggest that results in women with CVD or hypertension at baseline are confounded by postrandomization use of cholesterol-lowering medications.Conclusions: CVD risk in postmenopausal women appears to be sensitive to a change to a low-fat dietary pattern and, among healthy women, includes both CHD benefit and stroke risk. This trial was registered at clinicaltrials.gov as NCT00000611.

Project description:BackgroundMeta-analyses of observational studies associate adherence to several dietary patterns with cognitive health. However, limited evidence from full scale, randomized controlled trials precludes causal inference regarding dietary effects on cognitive function.MethodsThe Women's Health Initiative (WHI) Dietary Modification (DM) randomized trial, in 48,835 postmenopausal women, included a subset of 1,606 WHI Memory Study (WHIMS) participants >= 65 years old, to assess low-fat dietary pattern influence on global cognitive function, evaluated with annual screening (Modified Mini-Mental State Examinations [3MSE]). Participants were randomized by a computerized, permuted block algorithm, stratified by age group and center, to a dietary intervention (40%) to reduce fat intake to 20% of energy and increase fruit, vegetable and grain intake or usual diet comparison groups (60%). The study outcome was possible cognition impairment (failed cognitive function screening) through the 8.5 year (median) dietary intervention. Those failing screening received a comprehensive, multi-phase cognitive function assessment to classify as: no cognitive impairment, mild cognitive impairment, or probable dementia. Exploratory analyses examined the composite endpoint of death after possible cognitive impairment through 18.7 years (median) follow-up. The WHI trials are registered at ClinicalTrials.gov:NCT00000611.FindingsAmong the 1,606 WHIMS participants, the dietary intervention statistically significantly reduced the incidence of possible cognitive impairment (n = 126; hazard ratio [HR] 0.59 95% confidence interval [CI] 0.38-0. 91, P = 0.01) with HR for dietary influence on subsequent mild cognitive impairment of 0.65 (95% CI 0.35-1.19) and HR of 0.63 (95% CI 0.19-2.10) for probable dementia (PD). Through 18.7 years, deaths from all-causes after possible cognitive impairment were non-significantly lower in the dietary intervention group (0.56% vs 0.77%, HR 0.83 95% CI 0.35 to 2.00, P = 0.16).InterpretationAdoption of a low-fat eating pattern, representing dietary moderation, significantly reduced risk of possible cognitive impairment in postmenopausal women.FundingSeveral Institutes of the US National Institutes of Health.

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Low-fat dietary pattern and cancer incidence in the Women's Health Initiative Dietary Modification Randomized Controlled Trial.

Publications

Low-fat dietary pattern and cancer incidence in the Women's Health Initiative Dietary Modification Randomized Controlled Trial.

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