Grab Some Cabbage and Cantaloupe After You Go Jogging
Lera S. Wenger
David Schlundt, Ph.D.
Health Psychology 115A
November 11, 1997
Breast Cancer Prevention
Every year for the last fifty years the number of
cases of breast cancer in women has steadily increased. The only
cancer that claims more women's lives in the United States is Lung Cancer.
(http://rex.nci.nih.gov/NCI_Pub_Interface/raterisk/rates42.html)
This naturally causes concern among women, and thus the question of prevention
is immediately asked. With prevention of lung cancer, the easiest
and most effective way is to avoid smoking completely. Breast cancer,
on the other hand does not have such a direct behavioral action that dramatically
changes a person's risk. There are many factors that cause a person
to be more at risk for breast cancer, and there is not one simple action
of prevention that is as established as not smoking is for lung cancer.
Risk Factors for Breast Cancer
There are numerous risk factors associated with
breast cancer. If a person has family members with breast cancer,
especially a mother or a sister, it greatly increases a woman's odds of
being diagnosed. Additionally, women who have their first child
before the age of twenty years old are less likely to have breast cancer
than women who were over thirty years old at the time of their first child's
birth or had no children at all. If a woman breast fed her babies,
her risk goes down as well. The chances become higher for a woman the earlier
she began menstruating during adolescence. (http://oncolink.upenn.edu/cancer_news/1994/excersise_bc.html)
Women of higher economic status, living in a more urban environment in
the northern United States, and who are married have the highest rates
of breast cancer. (http://rex.nci.nih.gov/NCI_Pub_Interface/raterisk/risks120.html)
Clearly, many factors contribute to
an individual's chance of having breast cancer; this report concentrates
on behavioral associated risk factors such as diet and exercise. Statistics
show how countries around the world have rather different rates of breast
cancer. From 1986 to 1988 the death rates of breast cancer victims
were compiled. England and Wales had the highest rate with 29.3 deaths
per 100,000 women with breast cancer. Other European countries
tended to have the highest rates, and Asian countries had the lowest.
Thailand had the lowest number of deaths with only one death per 100,000
women from 1986 to 1988. The United States ranked sixteenth of the
fifty countries in the survey with a rate of 22.4 deaths per 100,000 women.
(http://rex.nci.nih.gov/NCI_Pub_Interface/raterisk/rates42.html)
Incidence rates are roughly five times higher in
northern Europe and North America than in Asia. (International Agency for
Research on Cancer, 1992) It has been shown that when
women move from a country with a typically low rate of breast cancer to
one with a higher rate, the woman's risk gradually increases to that of
a typical woman in the country with the higher rate. Thus, environmental
and behavioral differences between the countries must play an important
role in an individual woman's breast cancer risk.
Dietary Fat
One theory of the large variance among the country's
incidences of breast cancer deals with the amount of fat the people in
each country consumes. As body weight and mass increase in a post
menopausal woman, so does her risk of breast cancer. (http://rex.nci.nih.gov/NCI_Pub_Interface/raterisk/risks120.html)
A person's external influences are most likely involved in causing genetic
mutations, that in turn cause cancer of the breast. Behaviors of
the person may stimulate the cancer growth initially, and that is why diet
can be very influential in determining the risk of breast cancer.
It is thought that the diet of an adolescent woman can be especially important,
because that is when breast cells are growing the most.
"Your food shall be your remedy," was written by
Hippocrates and still is valid considering that 20 - 60 percent of
all cancer deaths were influenced by the diet of the patient. A diet
low in fat intake reduces a person's general cancer risk. Breast
cancer deaths increase when tumors spread. This happens when tumors
spread to nearby tissue, which is invasion. Breast Cancer also
spreads when a tumor grows in a location in the body distant from the breast,
and that is called metastasis. Dr. Rose from the University of Pennsylvania
has shown that metastasis has increased in laboratory rats that have human
breast cancer cells in their mammary tissue. This increase was directly
correlated with the amount of omega-6 unsaturated fatty acids the rats
ingested. (http://oncolink.upenn.edu/cancer_news/1994/diet_cancer.html)
Dietary Fat and its Connection with Ovarian Hormones
A large multicentre randomized controlled trial found
that a low-fat, high-carbohydrate diet reduces the breasts' exposure to
ovarian hormones, which in turn helps to prevent breast cancer. (Boyd
1997) This long term study involved women that had 50% or greater
breast density of the breast area. All of the women were pre-menopausal.
The participants were between 30 and 65 years old. The mean age for
the enrolled subjects was 42-43 years old. There were 112 people
in the intervention group, and there were 104 control subjects. The
subjects had similar heights and weights. Additionally 24% of the
intervention group and 14% of the control group had at least one first-degree
relative that had cancer of the breast. The women were involved in
a randomized trial of dietary intervention. Its goal was to reduce
dietary fat to 15% of the the total calories consumed for the intervention
subjects. The participants were given general advice but were not
counseled about their intake of fat.
After two years of the conducting the study, the
intervention and control groups had very similar nutrient intakes records.
There were evident differences between the two groups in other areas of
concern. The mean percentage of energy that came from fat for the
intervention group fell from 34% to 21%. The control group's mean
percentage of energy derived from fat remained the same, because they did
not reduce their intake of saturated, monounsaturated and polyunsaturated
fat. The subjects in the intervention, on the other hand, did reduce
their consumption of those fats, and thus they had the drop in fat energy
percentages. The intervention group had a difference
of 12% in their intake of carbohydrates as well. Their total carbohydrate
consumption rose from 48% to 60%. The intervention group
also ate more fiber over the two year period. Their level of fiber
intake went from 16 to 19 grams a day. These dietary changes that
the intervention group developed were a significant difference from those
of the control group. The members of the intervention group
had no change in body weight over the two year period, where as the control
group gained about 1.3 kilograms on average. (Boyd 1997)
The goal of this study was to see if dietary changes
such as lowering fat intake, and increasing carbohydrates and fiber would
cause a difference in levels of plasma sex hormones. The proposed
theory was that lower levels of ovarian hormones would help reduce the
risk of breast cancer. The amount of the ovarian hormones, oestradiol
and progesterone, in the blood greatly changed over the two year
duration of the study. Blood was drawn from the subjects initially
and every year for the next two years. The intervention subjects
had an average reduction of oestradiol of 13.9%, where as the control group
had a 2.9% increase of the hormone. The level of oestradiol of the
intervention group was 20.3% lower than the control group after two years.
The change in oestradiol levels was present in the women's blood whether
it was before or after their menstrual cycle. There was an even more
drastic change in levels of progesterone between between the two groups
of women. The members in the intervention group had progesterone
levels that were 33% lower than the levels corresponding with the subjects
in the control group. (Boyd 1997)
The results from this randomized controlled trial
indicate that a low-fat, high-fiber, and high-carbohydrate diet reduces
ovarian hormones in women. Such plasma sex hormones are a stimulus
to cell division in the breast. Therefore by reducing the amount
of such hormones in women, the amount of exposure that their breasts receive
from ovarian hormones is also reduced. Additionally, the reason that
women have a 100-fold excess of breast cancer over men is due to the amount
of female sexual hormones in them. Naturally women have greater amounts
of ovarian hormones, thus putting them at a much higher risk for breast
cancer. A woman's chances of developing breast cancer is decreased
when her ovaries are removed. This also relates to how women who
start menstruating earlier and go through menopause later are at a higher
risk for breast cancer, because they are exposed to ovarian hormones over
a longer period of time. (Boyd 1997)
Moreover, populations where women tend to have lower
blood levels of ovarian hormones also have fewer cases of breast cancer
per capita. The amount of oestradiol in post-menopausal women in
American whites is on average three times higher than levels of recent
Asian migrants to Hawaii. Incidence rates of breast cancer are much
lower in Asia then in the United States. Populations with lower ovarian
hormone levels and lower levels of fat in their diet tend to have lower
incidence rates of breast cancer. Reducing dietary fat reduces plasma
sex hormones in women, and that in turn reduces a woman's chance of developing
breast cancer. (Boyd 1997)
Antioxidants, Fruits,Vegetables, Fiber, and Fish and Olive Oils
Women on low fat diets also have breasts that are less
dense. Lower breast density decreases the risk of breast cancer.
At U.C.L.A. Dr. Glaspy is conducting a study exploring what
a low fat diet along with soy and fish oil supplements would do to the
composition of the breast. The breast cells taken from the women
in the midst of the study had encouraging results. They had less
Omega 6 oils which increase metastasis, the spreading of breast cancer.
The women's breast cell samples also contained more Omega 3 oils which
help to keep the breast healthy by protecting it. (http://www.cnn.com/HEALTH/9704/02/breast.cancer/index.html)
Also, many countries with the lowest rates of breast cancer tend to have
fish for their main source of protein. Studies are currently
beginning to study if fish oil and vitamin E could reduce the incidence
of breast cancer. (http://www.cancer.org/bcn/report.html)
In addition to eating a low fat diet, eating
at least five fruits and vegetables a day may reduce your risk of cancer.
There is evidence that the cancer rates for various countries are inversely
proportional to the amount of fruits and vegetables eaten by the populations
there. Thus, the more fruits and vegetables consumed, the fewer cases
of cancer. (http://rex.nci.nih.gov/NCI_Pub_Interface/raterisk/risks73.html)
Fruits and vegetable have many beneficial aspects about them. They
have vitamin A and C, carotenoids, minerals, biochemical compounds, and
fiber. Each of these elements of fruits and vegetables ,in
addition to other biochemicals and nutrients in them , help to contribute
to a person's overall health as well as fight away cancer.
Studies reveal that nutrition may effect breast
cancer incidence. (Kimmack 1997) Antioxidants, including vitamins
A and C, selenium, carotenoids, zinc, copper, iron, and manganese, may
protect breast tissue from the development of cancer. These micro
nutrients do so by protecting the tissue from oxidant damage. Such
substances are the body's ammunition against cellular oxidative damage
due to toxic oxygen products. Free radicals and reactive oxygen molecules
are generated endogenously as a result of metabolic reactions.
They bind cellular components and react with unsaturated bonds of membrane
lipids, denature proteins, and attack nucleic acids. Such chemical
reactions directly influence cell and tissue damage. Additionally,
they are connected with age-related disorders and are thought to cause
cancer. Vitamins C and E, and carotenoids trap damage causing free
radicals. Selenium, zinc, copper, manganese, and iron are critical
components of antioxidants. Antioxidants may prevent cancer by reducing
and suppressing cellular damage caused by oxidants. (Kimmack 1997)
An additional reason to eat fruits and vegetables.
A recent study found that an increase in consumption
of fruits, vegetables, and olive oil was associated with a lower breast
cancer risk, whereas an increase in margarine increased the risk.
(http://oncolink.upenn.edu/cancer_news/1995/olive_oil.html)
Cruciferous vegetables (broccoli, cauliflower, brussels sprouts & cabbage)
have caught quite a bit of attention from researchers. Rodents who
eat a diet with dried cabbage have shown to have a reduced risk of breast
cancer. The positive outcome no longer occurred though when the rats
were eating a high fat diet along with the cabbage. One added benefit
of eating many fruits and vegetables is that people who do so generally
eat less fat and fewer calories overall. (http://oncolink.upenn.edu/cancer_news/1994/diet_cancer.html)
Fiber also plays an important role, and studies have revealed that there
is a reduction in the risk of breast cancer in women who consume
high fiber diets. (http://rex.nci.nih.gov/NCI_Pub_Interface/raterisk/risks73.html)
The connection among dietary fiber, vitamins A, C,
and E, and breast cancer risk was studied in the Canadian National Breast
Cancer Screening Study. (Kimmack 1997) In 1982, 56,837
women participated in a self administered diet history. Risk factors
included vitamin supplements and nutrient intake. From the 56,837,
519 developed breast cancer within the next six years. The diets
of all of the subjects were studied, and the amount of vitamin E intake
had a small but positive association with the incidence of breast cancer.
Additionally, there was a stronger relationship with consumption of
dietary fiber, pastas, cereals, and vegetables rich in vitamins A and C
with breast cancer risk. The more such foods were consumed, the lower
the breast cancer incidence.
Alcohol
Alcohol has also shown to have an influence on breast
cancer risk. If a woman drinks two drinks daily throughout her lifetime,
then her breast cancer risk may increase 40 to 70 percent.
(http://rex.nci.nih.gov/NCI_Pub_Interface/raterisk/risks120.html)
There is a connection between the amount of alcohol a woman drinks
and her risk for breast cancer. The younger a woman is when she is
initially is exposed to alcohol increases her individual odds of developing
breast cancer. Additionally there is a dose-response relationship
with breast cancer risk and alcohol consumption. Women who drank
15g of alcohol a day, which is more than one drink, had a significantly
higher risk for breast cancer. The risk related to such alcohol consumption
alone is higher than the risk of having a family history of breast cancer.
(Colditz 1995)
Exercise
It is not only what you ingest into your body
that can influence breast cancer prevention, but also what you do with
your body. Female athletes have a reduced risk of breast cancer.
(http://www.cancer.org/bcn/report.html)
Additionally, women who get into the habit of exercising on a regular basis
have a better chance at fighting the odds. "Women who participate
in four or more hours of physical activity per week during their reproductive
years reduce their risk of breast cancer by 60 percent, compared to inactive
women." (http://oncolink.upenn.edu/cancer_news/1994/excersize_bc.html)
The most significant reduction in risk was associated with women jogging,
swimming laps, or playing tennis. It was also shown that regular
exercise, even though possibly only a couple hours a week, also helps to
reduce a woman's risk of developing breast cancer.
Conclusion
Recommendations for preventing breast cancer would include
many aspects of a person's behavior. A low fat diet is strongly suggested,
and no more than 30% of total calories should be calories from fat.
A diet with only 20% of its calories coming from fat is a reasonable goal.
In addition to limiting fat intake, it is important to increase consumption
of carbohydrates and fiber. Fruits and vegetables should replace
fatty foods in one's diet. Foods with complex carbohydrates,
fruits and vegetables not only contain antioxidants, but also quite a bit
of fiber. Cuciferous vegetables should also become part of one's
diet. Fish is a healthy alternative that often has less fat than
other meats. Additionally its oil can be beneficial for preventing
breast cancer. Consumption of alcohol should be minimal. Exercise
should become part of a daily routine, and one should try and be active
at least four hours a week.
There is quite a bit of evidence concerning prevention
of breast cancer, and numerous studies are currently being run across the
country. Unfortunately many American women think only of screening
for breast cancer, not preventing it. Clearly screening is critical
for early detection, but most women do not realize they may have a chance
at decreasing their odds for developing breast cancer by modifying their
behavior. During a telephone survey in 1995, only 23% of the women
cited dietary factors such as reducing fat and increasing fruits, vegetables,
and fiber as a way of reducing their personal risk for breast cancer.
(Barnard 1997)
There is no doubt eating a low fat diet is related
with overall good health, and more and more studies are revealing the positive
outcomes dealing with breast cancer prevention as well. The behavioral
aspects of everyday life must not be forgotten when one considers her personal
risk for breast cancer. There is reason why countries have such a
varied number of breast cancer incidences. Thus, behavioral and environmental
factors must be considered along with genetics in regards to breast cancer
risk assessment and prevention.
Bibliography
Barnard, N.D., and A. Nicholson. "Beliefs about Dietary Factors in
Breast Cancer
Prevention among American Women, 1991 to 1995."
Preventive Medicine 26
(1997) : 109-113.
Boyd, N. F., G. A. Lockwood, C. V. Greenberg, L. J. Martin, and D. L.
Tritchler.
"Effects of a low-fat high carbohydrate diet on
plasma sex hormones in pre-menopausal women:
results from a randomized controlled trial."
British Journal of Cancer 76 (1997) 127-135.
Coldritz G. A. and A. L. Frazier. "Models of Breast Cancer Show
that Risk is set by Events
of Early Life: Prevention Efforts Must Shift Focus."
Cancer Epidemiology, Biomarkers &
Prevention. 4 (1995) 567-571.
Kimmick, G.G., R.A. Bell, and R.M. Bostick. "Vitamin E and
Breast Cancer: a review."
27 (1997) 109-117.
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