Soy and Cancer Prevention Abstracts
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AUTHOR: Hebert JR; Hurley TG; Olendzki BC; Teas J; Ma Y; Hampl JS
ADDRESS: Division of Preventive and Behavioral Medicine, University
of Massachusetts Medical School, Worcester 01655, USA.
TITLE: Nutritional and socioeconomic factors in relation to
prostate cancer mortality: a cross-national study
SOURCE: J Natl Cancer Inst (J9J), 1998 Nov 4; 90 (21): 1637-47
LANGUAGE: English
COUNTRY PUB.: UNITED STATES
ABSTRACT:
BACKGROUND: Large international variations in rates of
prostate cancer incidence and mortality suggest that
environmental factors have a strong influence on the
development of this disease. The purpose of this study was
to identify predictive variables for prostate cancer
mortality in data from 59 countries. METHODS: Data on
prostate cancer mortality, food consumption, tobacco use,
socioeconomic factors, reproductive factors, and health
indicators were obtained from United Nations sources. Linear
regression models were fit to these data. The influence of
each variable fit in the regression models was assessed by
multiplying the regression coefficient b by the 75th (X75)
and 25th (X25) percentile values of the variable. The
difference, bX75 - bX25, is the estimated effect of the
variable across its interquartile range on mortality rates
measured as deaths per 100000 males aged 45-74 years.
Reported P values are two-sided. RESULTS: Prostate cancer
mortality was inversely associated with estimated
consumption of cereals (bX75 - bX25 = -7.31 deaths; P =
.001), nuts and oilseeds (bX75 - bX25 = -1.72 deaths; P =
.003), and fish (bX75 - bX25 = -1.47 deaths; P = .001). In
the 42 countries for which we had appropriate data, soy
products were found to be significantly protective (P =
.0001), with an effect size per kilocalorie at least four
times as large as that of any other dietary factor. Besides
variables related to diet, we observed an association
between prostate cancer mortality rates and a composite of
other health-related, sanitation, and economic variables (P
= .003). CONCLUSIONS: The specific food-related results from
this study are consistent with previous information and
support the current dietary guidelines and hypothesis that
grains, cereals, and nuts are protective against prostate
cancer. The findings also provide a rationale for future
study of soy products in prostate cancer prevention trials.
AUTHOR: Jacobsen BK; Knutsen SF; Fraser GE
ADDRESS: Institute of Community Medicine, University of Troms9,
Norway.
TITLE: Does high soy milk intake reduce prostate cancer incidence?
The Adventist Health Study (United States)
SOURCE: Cancer Causes Control (A5R), 1998 Dec; 9 (6): 553-7
LANGUAGE: English
COUNTRY PUB.: NETHERLANDS
ABSTRACT:
OBJECTIVES: Recent experimental studies have suggested that
isoflavones (such as genistein and daidzein) found in some
soy products may reduce the risk of cancer. The purpose of
this study was to evaluate the relationship between soy
milk, a beverage containing isoflavones, and prostate cancer
incidence. METHODS: A prospective study with 225 incident
cases of prostate cancer in 12,395 California Seventh-Day
Adventist men who in 1976 stated how often they drank soy
milk. RESULTS: Frequent consumption (more than once a day)
of soy milk was associated with 70 per cent reduction of the
risk of prostate cancer (relative risk = 0.3, 95 percent
confidence interval 0.1-1.0, p-value for linear trend =
0.03). The association was upheld when extensive adjustments
were performed. CONCLUSIONS: Our study suggests that men
with high consumption of soy milk are at reduced risk of
prostate cancer. Possible associations between soy bean
products, isoflavones and prostate cancer risk should be
further investigated.
AUTHOR: Zheng W; Dai Q; Custer LJ; Shu XO; Wen WQ; Jin F; Franke AA
ADDRESS: School of Public Health and Cancer Center, University of
South Carolina, Columbia 29203, USA.
TITLE: Urinary excretion of isoflavonoids and the risk of breast
cancer.
SOURCE: Cancer Epidemiol Biomarkers Prev (BNJ), 1999 Jan; 8 (1): 35-40
LANGUAGE: English
COUNTRY PUB.: UNITED STATES
ABSTRACT:
Isoflavonoids are a group of biologically active
phytochemicals that humans are exposed to mainly through soy
food intake. Because of the similar chemical structure of
these compounds and estradiol, it has been hypothesized that
isoflavonoids may be related to the risk of breast cancer.
Overnight urine samples from 60 incident breast cancer cases
and their individually matched controls were assayed for
urinary excretion rates of five major isoflavonoids
(daidzein, genistein, glycitein, equol, and O-
desmethylangolensin) and total phenols. These subjects were
from a large population-based case-control study conducted
in Shanghai, and urine samples from breast cancer cases were
collected before any cancer therapy to minimize the
potential influence of the disease and its sequelae on study
results. Urinary excretion of total phenols and all
individual isoflavonoids, particularly glycitein, was
substantially lower in breast cancer cases than controls.
For total isoflavonoids, the mean excretion was 13.95
nmol/mg creatinine (SD, 20.76 nmol/mg creatinine) for cases
and 19.52 nmol/mg creatinine (SD, 25.36 nmol/mg creatinine)
for controls (P for difference = 0.04). The case-control
difference was more evident when median levels of these
compounds were compared, with the median excretion of all
major isoflavonoids being 50-65% lower in cases than in
controls. Individuals in the highest tertile of daidzein,
glycitein, and total isoflavonoids had about half the cancer
risk of those in the lowest tertile. The adjusted odds ratio
for breast cancer was 0.14 (95% confidence interval, 0.02-
0.88) for women whose urinary excretion of both phenol and
total isoflavonoids was in the upper 50% compared with those
in the lower 50%. The results from this study support the
hypothesis that a high intake of soy foods may reduce the
risk of breast cancer.
AUTHOR: Xu X; Duncan AM; Merz BE; Kurzer MS
ADDRESS: Department of Food Science and Nutrition, University of
Minnesota, St. Paul 55108, USA.
TITLE: Effects of soy isoflavones on estrogen and phytoestrogen
metabolism in premenopausal women.
SOURCE: Cancer Epidemiol Biomarkers Prev (BNJ), 1998 Dec; 7 (12):
1101-8
LANGUAGE: English
COUNTRY PUB.: UNITED STATES
ABSTRACT:
Isoflavones and lignans are soy phytoestrogens that have
been suggested to be anticarcinogenic. The mechanisms by
which they exert cancer-preventive effects may involve
modulation of estrogen synthesis and metabolism. To evaluate
this hypothesis, a randomized, cross-over soy isoflavone
feeding study was performed in 12 healthy premenopausal
women. The study consisted of three diet periods, each
separated by a washout of approximately 3 weeks. Each diet
period lasted for three menstrual cycles plus 9 days
(averaging approximately 100 days), during which subjects
consumed their habitual diets supplemented with soy protein
powder providing 0.16 (control diet), 1.01, or 2.01 mg of
total isoflavones per kg of body weight per day (10+/-1.1,
65+/-9.4, or 129+/-16 mg/day, respectively). A 72-h urine
sample was collected during the midfollicular phase (days 7-
9) of the fourth menstrual cycle in each diet period. Urine
samples were analyzed for 10 phytoestrogens and 15
endogenous estrogens and their metabolites by a capillary
gas chromatography-mass spectrometry method. Urinary
excretion of isoflavonoids and lignans significantly
increased with increased isoflavone consumption. Compared
with the control diet, increased isoflavone consumption
decreased urinary excretion of estradiol, estrone, estriol,
and total estrogens, as well as excretion of the
hypothesized genotoxic estrogen metabolites, 16alpha-
hydroxyestrone, 4-hydroxyestrone, and 4-hydroxyestradiol. Of
importance are the observations of a significant increase in
the 2-hydroxyestrone/16alpha-hydroxyestrone ratio and a
decrease in the genotoxic/total estrogens ratio. These data
suggest that soy isoflavone consumption may exert cancer-
preventive effects by decreasing estrogen synthesis and
altering metabolism away from genotoxic metabolites toward
inactive metabolites.
AUTHOR: Messina MJ; Persky V; Setchell KD; Barnes S
ADDRESS: National Cancer Institute, National Institutes of Health,
Bethesda, MD.
TITLE: Soy intake and cancer risk: a review of the in vitro and in
vivo data.
SOURCE: Nutr Cancer (O94), 1994; 21 (2): 113-31
LANGUAGE: English
COUNTRY PUB.: UNITED STATES
ABSTRACT:
International variations in cancer rates have been
attributed, at least in part, to differences in dietary
intake. Recently, it has been suggested that consumption of
soyfoods may contribute to the relatively low rates of
breast, colon, and prostate cancers in countries such as
China and Japan. Soybeans contain a number of
anticarcinogens, and a recent National Cancer Institute
workshop recommended that the role of soyfoods in cancer
prevention be investigated. In this review, the hypothesis
that soy intake reduces cancer risk is considered by
examining relevant in vitro, animal, and epidemiological
data. Soybeans are a unique dietary source of the isoflavone
genistein, which possesses weak estrogenic activity and has
been shown to act in animal models as an antiestrogen.
Genistein is also a specific inhibitor of protein tyrosine
kinases; it also inhibits DNA topoisomerases and other
critical enzymes involved in signal transduction. In vitro,
genistein suppresses the growth of a wide range of cancer
cells, with IC50 values ranging from 5 to 40 microM (1-10
micrograms/ml). Of the 26 animal studies of experimental
carcinogenesis in which diets containing soy or soybean
isoflavones were employed, 17 (65%) reported protective
effects. No studies reported soy intake increased tumor
development. The epidemiological data are also inconsistent,
although consumption of nonfermented soy products, such as
soymilk and tofu, tended to be either protective or not
associated with cancer risk; however, no consistent pattern
was evident with the fermented soy products, such as miso.
Protective effects were observed for both hormone- and
nonhormone-related cancers. While a definitive statement
that soy reduces cancer risk cannot be made at this time,
there is sufficient evidence of a protective effect to
warrant continued investigation.
AUTHOR: Thiagarajan DG; Bennink MR; Bourquin LD; Kavas FA
ADDRESS: Department of Food Science and Human Nutrition, Michigan
State University, East Lansing 48824-1224, USA.
TITLE: Prevention of precancerous colonic lesions in rats by soy
flakes, soy flour, genistein, and calcium.
SOURCE: Am J Clin Nutr (3EY), 1998 Dec; 68 (6 Suppl): 1394S-1399S
LANGUAGE: English
COUNTRY PUB.: UNITED STATES
ABSTRACT:
The main purpose of this research was to determine whether
diets containing soy products would inhibit the early stages
of azoxymethane-induced colon cancer in F344 rats.
Additional objectives were to determine whether feeding
starch instead of sucrose, feeding additional calcium (0.5%
compared with 0.1%), or feeding a low-fiber powdered enteral
formula would influence early colon carcinogenesis. Colon
cancer was initiated with 2 injections of azoxymethane (15
mg/kg body wt) and a 12-wk dietary treatment period was
started 1 wk after the second injection. Precancerous colon
lesions were assessed as foci with aberrant crypts (FAC).
The mean numbers of FAC were 133 [soy concentrate (low
concentration of phytochemicals)], 111 (starch substituted
for sucrose), 98 [full-fat soy flakes (whole soybeans)], 87
(defatted soy flour), 77 (0.015% genistein), and 70 (0.5%
Ca). The soy flour and full-fat soy flake diets contained
0.049% genistein derivatives (primarily glycosides), but
were less effective in inhibiting the formation of FAC than
the diet containing 0.015% genistein (as the aglycone).
Eating soybeans and soy flour may reduce the early stages of
colon cancer.
AUTHOR: Le Marchand L; Hankin JH; Wilkens LR; Kolonel LN; Englyst
HN; Lyu LC
ADDRESS: Etiology Program, University of Hawaii Cancer Research
Center, Honolulu, USA.
TITLE: Dietary fiber and colorectal cancer risk.
SOURCE: Epidemiology (A2T), 1997 Nov; 8 (6): 658-65
LANGUAGE: English
COUNTRY PUB.: UNITED STATES
ABSTRACT:
We conducted a population-based case-control study among
different ethnic groups in Hawaii to evaluate the role of
various types and components of fiber, as well as
micronutrients and foods of plant origin, on the risk of
colorectal cancer. We administered personal interviews to
698 male and 494 female Japanese, Caucasian, Filipino,
Hawaiian, and Chinese cases diagnosed during 1987-1991 with
adenocarcinoma of the colon or rectum and to 1,192
population controls matched to cases by age, sex, and
ethnicity. We used conditional logistic regression to
estimate odds ratios, adjusted for caloric intake and other
covariates. We found a strong, dose-dependent, inverse
association in both sexes with fiber intake measured as
crude fiber, dietary fiber, or nonstarch polysaccharides. We
found inverse associations of similar magnitude for the
soluble and insoluble fiber fractions and for cellulose and
noncellulosic polysaccharides. This protective effect of
fiber was limited to fiber from vegetable sources, with an
odds ratio of 0.6 (95% confidence interval = 0.4-0.9) and
0.5 (95% confidence interval = 0.3-0.7) for the highest
compared with the lowest quartile of intake for men and
women, respectively. We found associations of the same
magnitude for soluble and insoluble vegetable fiber, but no
clear association with fiber from fruits or cereals. This
pattern was consistent between sexes, across segments of the
large bowel (right colon, left colon, and rectum), and among
most ethnic groups. The effect of vegetable fiber may be
independent of the effects of other phytochemicals, since
the effect estimates remained unchanged after further
adjustment for other nutrients. Intakes of carotenoids,
light green vegetables, yellow-orange vegetables, broccoli,
corn, carrots, bananas, garlic, and legumes (including soy
products) were inversely associated with risk, even after
adjustment for vegetable fiber. The data support a
protective role of fiber from vegetables against colorectal
cancer, which appears independent of its water solubility
property and of the effects of other phytochemicals. The
data also indicate that certain vegetables and fruits may be
protective against this disease through mechanisms other
than their fiber content.
AUTHOR: Adlercreutz H
ADDRESS: Folkhalsan Research Centre, Department of Clinical
Chemistry, University of Helsinki, Finland.
TITLE: Epidemiology of phytoestrogens.
SOURCE: Baillieres Clin Endocrinol Metab (9JL), 1998 Dec; 12 (4):
605-23
LANGUAGE: English
COUNTRY PUB.: ENGLAND
ABSTRACT:
Epidemiological studies have revealed that high levels of
lignans and isoflavonoids are frequently associated with low
breast, prostate and colon cancer risk, as well as a low
risk of coronary heart disease. These compounds seem to be
cancer protective and/or are biomarkers of a 'healthy' diet.
All soy protein products consumed by Asian populations have
high concentrations of isoflavonoids. In other countries,
such as Finland and Sweden, the lignan levels are higher in
populations with the lowest risk because of a high
consumption of whole-grain rye bread, berries and some
vegetables. There is a strong association between fibre
intake per kilogram body weight and lignan concentrations in
body fluids. Breast cancer has been found to be associated
with low lignan levels in the USA, Finland, Sweden and
Australia. With regard to prostate and colon cancer, as well
as coronary heart disease, the epidemiological data related
to phytoestrogens are still very limited.
AUTHOR: Moyad MA
ADDRESS: Section of Urology, University of Michigan, Ann Arbor 48109-
0330, USA.
TITLE: Soy, disease prevention, and prostate cancer.
SOURCE: Semin Urol Oncol (CBS), 1999 May; 17 (2): 97-102
LANGUAGE: English
COUNTRY PUB.: UNITED STATES
ABSTRACT:
Population-based studies from around the world support the
theory that soy products and their constituents, primarily
the isoflavones or phytoestrogens, are partly responsible
for the lower rates of certain chronic diseases in different
areas of the world. Cardiovascular disease and hormonally
induced cancers are just a few of the conditions lower in
Asian countries that consume large quantities of soy per
average person. Genistein, one of soy's individual
phytoestrogens, has been found to inhibit numerous breast
and prostate cancer cell lines. A limited amount of clinical
evidence also points to a beneficial role of soy in reducing
hormonal levels and exhibiting weak estrogen and
antiestrogen-like qualities. Other phytoestrogens found in
nature, such as lignans, may also have a future role in
cancer. Collectively, these phytoestrogens, like genistein,
have enough evidence to warrant their use in a number of
clinical trials as a potential chemopreventive agent or
adjunct to prostate cancer treatment.
AUTHOR: Li Y; Upadhyay S; Bhuiyan M; Sarkar FH
ADDRESS: Department of Pathology, Karmanos Cancer Institute at Wayne
State University School of Medicine, Detroit, Michigan
48201, USA.
TITLE: Induction of apoptosis in breast cancer cells MDA-MB-231 by
genistein.
SOURCE: Oncogene (ONC), 1999 May 20; 18 (20): 3166-72
LANGUAGE: English
COUNTRY PUB.: ENGLAND
ABSTRACT:
Breast cancer is the most common cancer among American
women, whereas Asian women, who consume a traditional diet
high in soy products, have a relatively low incidence.
Genistein is a prominent isoflavonoid in soy products and
has been proposed as the agent responsible for lowering the
rate of breast cancer in Asian women. We investigated the
effects of genistein on cell growth and apoptosis-related
gene expression in breast cancer cells MDA-MB-231. We found
up-regulation of Bax and p21WAF1 expressions and down-
regulation of Bcl-2 and p53 expression in genistein-treated
cells. Furthermore, DNA ladder formation, CPP32 activation,
and PARP cleavage were observed after treatment with
genistein, indicating apoptotic cell deaths. Flow cytometry
with 7-amino actinomycin D staining showed that the number
of apoptotic cells increased with longer treatment of
genistein. From these results, we conclude that genistein
inhibits the growth of MDA-MB-231 breast cancer cells,
regulates the expression of apoptosis-related genes, and
induces apoptosis through a p53-independent pathway. The up-
regulation of Bax and p21WAF1 may be the molecular
mechanisms by which genistein induces apoptosis, however,
further definitive studies are needed. These results suggest
that genistein may be a potentially effective
chemopreventive or therapeutic agent against breast cancer.
AUTHOR: Davis JN; Singh B; Bhuiyan M; Sarkar FH
ADDRESS: Department of Cancer Biology, Wayne State University School
of Medicine, Harper Hospital, Detroit Medical Center, MI,
USA.
TITLE: Genistein-induced upregulation of p21WAF1, downregulation of
cyclin B, and induction of apoptosis in prostate cancer
cells.
SOURCE: Nutr Cancer (O94), 1998; 32 (3): 123-31
LANGUAGE: English
COUNTRY PUB.: UNITED STATES
ABSTRACT:
Increased soy consumption in Asian diets, resulting in
increased serum isoflavone levels, has been associated with
a decreased risk for prostate adenocarcinoma (PCa). The
isoflavone genistein is believed to be the anticancer agent
found in soy, and significant levels of genistein have been
detected in human prostatic fluid, implicating the role of
genistein in PCa prevention. Recent studies have
demonstrated genistein's ability to inhibit cell growth and
induce apoptosis in several cell lines; however, the
molecular mechanisms of genistein's effect are not known. We
have evaluated the mechanism by which genistein may inhibit
PCa cell growth. Here we report that genistein inhibits PCa
cell growth in culture in a dose-dependent manner, which is
accompanied by a G2/M cell cycle arrest. Cell growth
inhibition was observed with concomitant downregulation of
cyclin B, upregulation of the p21WAF1 growth-inhibitory
protein, and induction of apoptosis. Collectively, these
results provide experimental evidence for a novel effect of
genistein on cell cycle gene regulation, resulting in the
inhibition of cell growth and ultimate demise of tumor
cells.
AUTHOR: Fair WR; Fleshner NE; Heston W
ADDRESS: Department of Surgery, Memorial Sloan-Kettering Cancer
Center, New York, NY 10021, USA.
TITLE: Cancer of the prostate: a nutritional disease?
SOURCE: Urology (WSY), 1997 Dec; 50 (6): 840-8
LANGUAGE: English
COUNTRY PUB.: UNITED STATES
ABSTRACT:
In summary, epidemiologic and laboratory evidence
increasingly demonstrate that nutritional factors,
especially reduced fat intake, soy proteins, vitamin E
derivatives, and selenium, may have a protective effect
against prostate cancer. The experimental observation that
low-fat diets and soy protein extracts may influence the
progression of established tumors, rather than inhibiting
etiologic factors, is particularly intriguing because it may
serve to help explain the paradox whereby the incidence of
clinical prostate cancer shows wide geographic variation,
yet the evidence persists that the incidence of microfocal
tumors is essentially the same worldwide. These
observations, plus the likelihood that nutrition trials are
likely to have little in the way of toxicity that would
preclude their completion, argue that such trials should be
performed. It is estimated that 30% to 50% of human
malignancies may be related to dietary factors, and although
the feasibility of trials involving low-fat diets has been
proved in ongoing trials for colon and breast cancer, no
similar study exists for prostate malignancy. Critics of
epidemiologic research argue that data derived from case-
control studies are subject to recall bias and are thus
artifactual. Indeed, many researchers now believe that the
breast cancer-dietary fat hypothesis has been discredited.
The major difference between the prostate cancer and breast
cancer literature is the remarkable consistency of the
cohort studies. In these studies, exposure is determined
prospectively and is therefore free from recall bias. In
this sense they more closely resemble a clinical trial. The
majority of cohort studies involving dietary fat and breast
cancer have been negative. We believe that these data
justify large-scale trials in the area of prevention of
prostate cancer. One such proposed study already submitted
for National Institutes of Health funding from a consortium
of centers is the Prostate Interventional Nutrition Study
(PINS), modeled after the Women's Interventional Nutrition
Study, which investigates the effect of low-fat diets in
women receiving therapy for node-positive breast cancer. The
PINS study will be limited to men who have detectable serum
PSA levels but no other clinical evidence of disease after
radical prostatectomy. All subjects will receive nutritional
guidance, with randomization between a control arm receiving
the currently recommended 30% fat diet and an interventional
arm in which a 15% fat diet is supplemented with soy
protein, vitamin E, and selenium. The end points for
evaluation will be compared with progression based on
changes in PSA and the time of onset of clinical, as opposed
to biochemical, disease. Single-institution trials involving
groups thought to be at high risk of developing clinical
cancer--including men with persistently elevated PSA levels,
two negative prostate biopsies, high-grade prostatic
intraepithelial neoplasia on biopsy, and a strong family
history of prostate cancer--are being initiated at MSKCC and
other institutions. CONCLUSIONS: We have reviewed the
evidence that nutritional factors play a role in the
progression rate of prostate cancer and may help to explain
the geographic variation in the incidence observed. However,
without well-controlled prospective trials, the attractive
hypothesis that nutrition plays a role in tumor progression
remains simply an attractive hypothesis. To date, no
definite proof of a preventive effect has been shown in a
study that will withstand rigid scientific scrutiny. The
opportunity exists, however, for the urologic community,
working together with experts in the area of nutrition, not
only to advance our understanding of prostate tumorigenesis,
but to rebut those critics of modern medical technology who
claim that we have ignored the total or holistic approach to
healing. (ABSTRACT TRUNCATED)
AUTHOR: Goodman MT; Wilkens LR; Hankin JH; Lyu LC; Wu AH; Kolonel LN
ADDRESS: Epidemiology Program, Cancer Research Center of Hawaii,
University of Hawaii, Honolulu, USA.
TITLE: Association of soy and fiber consumption with the risk of
endometrial cancer.
SOURCE: Am J Epidemiol (3H3), 1997 Aug 15; 146 (4): 294-306
LANGUAGE: English
COUNTRY PUB.: UNITED STATES
ABSTRACT:
The authors conducted a case-control study among the multi-
ethnic population of Hawaii to examine the role of dietary
soy, fiber, and related foods and nutrients on the risk of
endometrial cancer. Endometrial cancer cases (n = 332)
diagnosed between 1985 and 1993 were identified from the
five main ethnic groups in the state (Japanese, Caucasian,
Native Hawaiian, Filipino, and Chinese) through the rapid-
reporting system of the Hawaii Tumor Registry. Population
controls (n = 511) were selected randomly from lists of
female Oahu residents and matched to cases on age (+/-2.5
years) and ethnicity. All subjects were interviewed using a
diet history questionnaire that included over 250 food
items. Non-dietary risk factors for endometrial cancer
included nulliparity, never using oral contraceptives,
fertility drug use, use of unopposed estrogens, a history of
diabetes mellitus or hypertension, and a high Quetelet's
index (kg/cm2). Energy intake from fat, but not from other
sources, was positively associated with the risk of
endometrial cancer. The authors also found a positive,
monotonic relation of fat intake with the odds ratios for
endometrial cancer after adjustment for energy intake. The
consumption of fiber, but not starch, was inversely related
to risk after adjustment for energy intake and other
confounders. Similar inverse gradients in the odds ratios
were obtained for crude fiber, non-starch polysaccharide,
and dietary fiber. Sources of fiber, including cereal and
vegetable and fruit fiber, were associated with a 29-46%
reduction in risk for women in the highest quartiles of
consumption. Vitamin A and possibly vitamin C, but not
vitamin E, were also inversely associated with endometrial
cancer, although trends were not strong. High consumption of
soy products and other legumes was associated with a
decreased risk of endometrial cancer (p for trend = 0.01;
odds ratio = 0.46, 95% confidence interval 0.26-0.83) for
the highest compared with the lowest quartile of soy intake.
Similar reductions in risk were found for increased
consumption of other sources of phytoestrogens such as whole
grains, vegetables, fruits, and seaweeds. Ethnic-specific
analyses were generally consistent with these results. The
observed dietary associations appeared to be largely
independent of other risk factors, although the effects of
soy and legumes on risk were limited to women who were never
pregnant or who had never used unopposed estrogens. These
data suggest that plant-based diets low in calories from
fat, high in fiber, and rich in legumes (especially
soybeans), whole grain foods, vegetables, and fruits reduce
the risk of endometrial cancer. These dietary associations
may explain in part the reduced rates of uterine cancer in
Asian countries compared with those in the United States.
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