Hooper et al included The Women's Intervention Nutrition
Study (WINS) as a reduced fat trial in their 2012
meta-analysis and as a reduced SFA trial in their 2015
meta-analysis
Studies
Associated with the Trial
Dietary fat reduction in adjuvant breast cancer therapy:
current rationale and feasibility issues (1990) (no URL and no access)
Effects of tamoxifen adjuvant therapy and a low-fat diet
on serum binding proteins and estradiol bioavailability in postmenopausal
breast cancer patients (1992) [1]
The effects of a low-fat dietary intervention and
tamoxifen adjuvant therapy on the serum estrogen and sex hormone-binding
globulin concentrations of postmenopausal breast cancer patients (1993) [2]
Adherence to a dietary fat intake reduction program in
postmenopausal women receiving therapy for early breast cancer. The Women's
Intervention Nutrition Study (1993) [3]
The challenges of assessing fat intake in cancer research
investigations (1997) [4]
Dietary fat reduction and breast cancer outcome: interim
efficacy results from the women's intervention nutrition study (2006) [5]
Implementing a low-fat eating plan in the Women's
Intervention Nutrition Study [6]
Methods
The basis of this trial was that ecological and animal
studies suggested a link between fat intake and the development of cancer (but
cohort studies didn’t) [4]. “The Women's Intervention Nutrition Study
(WINS) was subsequently designed to test the hypothesis that a dietary
intervention targeting fat intake reduction would prolong relapse-free survival
in women with resected breast cancer.” [5]
Women aged between 48-79 with breast cancer (other
criteria listed here [5])
were randomised to a reduced fat group or a control group. The participants were similar at baseline (table
1 and table
2) [5]
The reduced fat group were given a fat gram goal to reduce
fat intake to 15% while maintaining weight, with the researchers expecting this
would be maintained at 20% of total calories based on an earlier feasibility
study. Other methods to reduce fat
intake included dietary counselling, goal setting, self-monitoring and social
support (see [5] [6] for more info).
“Those classified
as “strictly adherent” who met their fat gram goal not only decreased their
intake of discretionary fat from oils, sweets and fat, but also reduced their
intake of sweet breads, pastries, and desserts; cheese; poultry, beef, pork,
and lamb; nuts and seeds; and eggs to a greater degree than did those who were
not strictly adherent” [6]
Results
The experimental group maintained a fat intake of ~20% at
1 year and despite aiming to maintain weight, the reduced fat group lowered
their calorie intake and lost a small amount of weight [5]. This was also fairly well maintained for 6
years as fat intake only crept up to ~23% [6]. After 5 years the reduced fat group lost 4.6
lb while the control group gained 1.7 lb [6].
|
Experimental
Group
|
Control Group
|
||
Baseline
|
1 Year
|
Baseline
|
1 Year
|
|
Energy (kcal)
|
1687
|
1460
|
1531
|
1660
|
Total fat
|
57.3 (29.6%)
|
33.3 (20.3%)
|
51.3 (29.2%)
|
56.3 (29.6%)
|
SFA (g)
|
18.7
|
10.4
|
16.6
|
18.5
|
MUFA (g)
|
21.6
|
12.3
|
19.6
|
21.3
|
PUFA (g)
|
12.2
|
7.3
|
10.8
|
11.9
|
Fibre (g)
|
18.4
|
19.5
|
17.3
|
18.0
|
BMI
|
27.6
|
26.8
|
27.5
|
27.6
|
The experimental group had a lower incidence of relapse
after a median of 5 years (also see table
4). “Based on the effects on the
primary endpoint, 38 women would need to adopt a lifestyle intervention
reducing dietary fat intake to prevent one additional breast cancer recurrence”
[5]
|
Hazard Ratio
(95% CI)
|
P value
|
Relapse free survival
|
0.76 (0.60-0.98)
|
0.077
|
Recurrence free survival
(excluding contralateral breast cancers)
|
0.71 (0.53-0.94)
|
0.050
|
Disease free survival
|
0.81 (0.65-0.99)
|
0.078
|
Overall survival
|
0.89 (0.65-1.21)
|
0.560
|
Hooper et al was not able to get information on CVD
events or mortality so they only total mortality (which comes from “Death (without
breast cancer recurrence)” in table
4)
|
Experimental
|
Control
|
Risk Ratio
|
Total Mortality
|
15/975
|
19/1462
|
1.18
|
Hooper et al assessed this trial as having a high risk of
bias in ‘systematic difference in care’ and a low risk of bias in ‘dietary
differences other than fat’
This concludes my series of blog posts on the clinical
trials that have been included in meta-analyses related to saturated fat and/or
polyunsaturated fat and coronary heart disease
No comments:
Post a Comment