LE Magazine May 2002
Page 1 of 4
Breast cancer/vitamin E
Does lack of tocopherols and
tocotrienols put women at increased risk of breast cancer?
Breast cancer is the leading site of new cancers in women
and the second leading cause (after lung cancer) of cancer
mortality in women. Observational studies that have collected
data for dietary exposure to alpha-tocopherol with or without
the other related tocopherols and tocotrienols have suggested
that vitamin E from dietary sources may provide women with
modest protection from breast cancer. However, there is no
evidence that vitamin E supplements confer any protection
whatever against breast cancer. Observational studies that
have assessed exposure to vitamin E by plasma or adipose
tissue concentrations of alpha-tocopherol have failed to
provide consistent support for the idea that alpha-tocopherol
provides any protection against breast cancer. In addition,
evidence from studies in experimental animals suggest that
alpha-tocopherol supplementation alone has little effect on
mammary tumors. In contrast, studies in breast cancer cells
indicate that alpha- gamma-, and delta-tocotrienol, and to a
lesser extent delta-tocopherol, have potent antiproliferative
and proapoptotic effects that would be expected to reduce risk
of breast cancer. Many vegetable sources of alpha-tocopherol
also contain other tocopherols or tocotrienols. Thus, it seems
plausible that the modest protection from breast cancer
associated with dietary vitamin E may be due to the effects of
the other tocopherols and the tocotrienols in the diet.
Additional studies will be required to determine whether this
may be the case, and to identify the most active
tocopherol/tocotrienol.
J Nutr Biochem 2002
Jan;13(1):2-20
Diet and the risk of breast cancer in
a case-control study: does the threat of disease have an
influence on recall bias?
It has been suggested that recall bias may explain the
discrepant results between case-control and cohort studies on
diet and the risk of breast cancer. Two control groups were
used for this case-control study of 25 to 75-year-old breast
cancer cases (n = 310). The first group consisted of
population controls drawn from the Finnish National Population
Register (n = 454). The second group consisted of women who
were referred to the same examinations as were the cases
because of clinical suspicion of breast disease but who were
later diagnosed as healthy (referral controls; n = 506).
Because the diagnosis was unknown at the time of interview, it
was possible to assess by comparing the two control groups
whether the self-reporting of diet changed under the threat of
disease. Dietary habits were examined using a validated,
self-administered food-frequency questionnaire. Premenopausal
women misreported their consumption of liquid milk products,
tea and sugar. Reporting bias was also associated with the
intake of fat and vitamins. Postmenopausal women misreported
consumption of milk products. When recall bias was taken into
consideration, milk was associated with increased risk of
premenopausal breast cancer, whereas high consumption of
poultry or high intake of monounsaturated fatty acids, n-3
fatty acids, n-6 fatty acids and vitamin E were related to
lower risk. The study suggested that oil, milk, cheese, coffee
and beta-carotene may act as protective factors in
postmenopausal women, whereas butter and cream may be risk
factors for breast cancer. In summary, it is possible that
some food items may be overreported or underreported under the
threat of disease in health-conscious population. However,
most of the results in this study were not modified by recall
bias.
J Clin Epidemiol 1999
May;52(5):429-39
Interaction of family history of
breast cancer and dietary antioxidants with breast cancer risk
(New York, United States).
We sought to determine if specific dietary antioxidants may
be particularly effective in reducing breast cancer risk for
women reporting family history (FH) of breast cancer in a
first-degree relative. Interviews regarding usual diet, health
and family histories were conducted with 262 premenopausal and
371 postmenopausal women with incident, primary breast cancer
from western New York (United States). These women were
frequency-matched by age and county of residence with
community controls. Among premenopausal women, there was a
significant interaction between FH and alpha-tocopherol;
alpha-tocopherol was associated with significantly decreased
risk among FH+ women (adjusted fourth-quartile odds ratio [OR]
= 0.01, 95 percent confidence interval [CI] = 0.0-0.3). This
association was much weaker for FH- women [OR = 0.7, CI =
0.4-1.2]. For FH- women, a significant inverse association was
observed between beta-carotene and premenopausal breast-cancer
risk (OR = 0.4, CI = 0.3-0.5), but not for FH+ women (OR =
0.5, CI = 0.1-4.0). Similar relationships, although not as
strong, were noted among postmenopausal women. Although
limited by small numbers, these results suggest that biologic
mechanisms of tumorigenesis may differ in FH+ and FH- women,
and that alpha-tocopherol may be a potential chemopreventive
agent for women with a family history of breast cancer,
particularly premenopausal women.
Cancer Causes Control 1995
Sep;6(5):407-15
Premenopausal breast cancer risk and
intake of vegetables, fruits and related nutrients.
BACKGROUND: Given the international variations in breast
cancer incidence rates and the changes in breast cancer
incidence among migrant populations, it has been hypothesized
that diet is a factor influencing risk of this disease. Many
studies indicate that a diet high in vegetables and fruits may
protect against breast cancer. PURPOSE: We conducted a
case-control study of diet, including the intake of non-food
supplements, and premenopausal breast cancer risk. We
evaluated in detail usual intake of vegetables and fruits
(each measured as the total reported grams consumed for all
queried vegetables and fruit), vitamins C and E, folic acid,
individual carotenoids and dietary fiber with its components.
METHODS: Case patients (n=297) were identified through
pathology records from hospitals in Erie and Niagara counties
in western New York. They consisted of premenopausal women 40
years of age or oder who were diagnosed with breast cancer
from November 1986 through April 1991. Control subjects
(n=311), frequency-matched to case patients on the basis of
age and county of residence, were randomly selected from New
York State Department of Motor Vehicles records. In-person
interviews included detailed reports of usual diet in the
period 2 years before the interview. Unconditional logistic
regression was used to estimate odds ratios (ORs) and 95%
confidence intervals (CIs). RESULTS: There was a reduction in
risk associated with high intake of several nutrients. With
the lowest quartile of intake as the referent, adjusted ORs
for the highest quartile of intake for specific nutrients were
as follows: vitamin C (OR=0.53; 95% CI=0.33-0.86),
alpha-tocopheral (OR=0.55; 95% CI=0.34-0.88), folic acid
(OR=0.50; 95% CI=0.31-0.82), alpha-carotene (OR=0.67; 95%
CI=0.42-1.08) and beta-carotene (OR=0.46; 95% CI=0.28-0.74),
lutein + zeaxanthin (OR=0.47; 95% CI=0.28.0-77), and dietary
fiber from vegetables and fruits (OR=0.48; 95% CI=0.30-0.78).
No association with risk was found for beta-cryptoxanthin,
lycopene, or grain fiber. Fruits were weakly associated with a
reduction in risk (fourth quartile OR=0.67; 95% CI=0.42-1.09).
No association was found between breast cancer risk and intake
of vitamins C and E and folic acid taken as supplements. A
strong inverse association between total vegetable intake and
risk was observed (fourth quartile OR=0.46; 95% CI=0.28-0.74).
This inverse association was found to be independent of
vitamin C,alpha-tocopherol, folic acid, dietary fiber, and
alpha-carotene. Adjusting for beta-carotene or lutein +
zeaxanthin somewhat attenuated the inverse association with
vegetable intake. CONCLUSIONS: In this population, intake of
vegetables appears to decrease premenopausal breast cancer
risk. This effect may be related, in part, to beta-carotene
and lutein + zeaxanthin in vegetables. It appears, however,
that, of the nutrients and food components examined, no single
dietary factor explains the effect. Evaluated components found
together in vegetables may have a synergistic effect on breast
cancer risk; alternatively, other unmeasured factors in these
foods may also influence risk.
J Natl Cancer Inst 1996 Mar
20;88(6):340-8
The role of fat, animal protein and
some vitamin consumption in breast cancer: a case control
study in southern France.
The role of the consumption of fat, animal protein and
vitamins on breast-cancer risk was investigated in a
hospital-based case-control study of 924 patients (409 cases
and 515 controls) in Montpellier (France). A dietary history
questionnaire, administered by interview, comprising 55 key
food items as well as beverage consumption, and including food
frequencies and portion sizes, was used to measure the intake
of total fat and its constituents, animal protein, retinol,
beta-carotene, vitamin E and alcohol consumption. The
questionnaire also elicited information on relevant medical
history and personal characteristics. All food items which
showed significantly elevated odds ratio (high-fat cheese,
desserts and chocolate and processed pork meat) in a
multivariate analysis contained a high proportion of animal
fat. This is reflected in the nutrient analysis, which showed
a significant linear trend as well as an elevated odds ratio
for the highest tertile of consumption of total fat [OR3 = 1.6
(1.1-2.2)], animal fat [OR3 = 1.6 (1.1-2.2)], saturated fat
[OR3 = 1.9 (1.3-2.6)] and mono-unsaturated fat [OR3 = 1.7
(1.2-2.5)]. For post-menopausal women, there is a particularly
strong association with saturated fat [OR3 = 3.3 (1.4-7.8)] in
a multivariate analysis including all other significant
nutrients. There is no evidence of an increase of risk with
the intake of animal protein and no evidence of risk reduction
with increased consumption of vegetables, beta-carotene or
vitamin E. Along with some recent studies, our results give
support to the hypothesis that dietary fat is a risk factor in
breast carcinogenesis.
Int J Cancer 1991 Apr
22;48(1):1-9\
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