Breast Cancer
by Joseph L. Mayo,MD Mary Ann
Mayo, MA
May 2, 1999
What do you fear most? Bankruptcy?
Floods? Heart disease? If you're like many women, breast
cancer stands near the top of that dreaded list.
But that fear doesn't permeate other cultures the way it
does ours.
A woman like Mariko Mori, for instance, 52 years old,
Japanese, worries about intense pressures beginning to
burden her toddler grandson. But worry about breast cancer?
Hardly.
In Indiana, Mary Lou Marks, 50, has similar family frets,
mulling over her 28-year-old daughter's career choice.
But on top of that, when Mary Lou tabulates her other
worries, she recoils at the thought of breast cancer. She's
heard about her lifetime risk: 1 in 8. Meanwhile, Mariko's
is merely 1 in 40, according to Bob Arnot's Breast Cancer
Prevention Diet (Little, Brown).
American Problem
Experts reporting in "Women at High Risk for Breast Cancer:
A Primary Care Perspective" (Prim Care Update Ob/Gyns, vol.
5, no. 6, 1998, p. 269) say the risk of developing breast
cancer for the average American woman during ages 40 to 59
is 3.9%; by 60 to 79 years of age that rises to 6.9%. A
high-risk 40-year-old has a 20% chance of breast cancer in
the next 20 years.
New studies have found the effect of carrying the gene
linked to breast cancer, which is responsible for only 5 to
10% of breast cancer incidence, is not as great as first
suspected. Earlier estimates that the gene reflects an 80%
chance of incurring breast cancer by age 70 has been
recalculated to be only 37% (The Lancet,
1998;352:1337-1339).
Complex Causesbr> Researchers agree: No
one factor is solely responsible for breast cancer. Risk
depends on many factors, including diet, weight, smoking,
alcohol consumption, activity level and, of course, those
genes.
Regardless of their actual chance of getting breast
cancer, women worry. Mary Lou faces no factors that would
place her in particular jeopardy. But her anxieties about
radical therapies and medical expenses paralyze her: She
forgets to visit her health care provider and skips her
annual mammogram appointments. Mary Lou's daughter, perhaps
in reaction to her mother's gripping fears, campaigns
ardently for cancer prevention, educating herself and
mobilizing against the cumulative effects of known cancer
risks. Smart young woman: A malignancy, after all, can take
years to develop. A tumor must swell to one billion cells
before it is detectable by a mammogram.
Dietary Benefits
Of all the tactics for reducing the risk of breast cancer,
diet ranks high on the list.
The soy-rich regimen of Japanese women like Mariko Mori,
for example, helps to explain the low breast cancer rates in
Asian countries (see box at center of the page).
Tomatoes, because of their high quotient of the
carotenoid lycopene, have been found to protect cells from
the corrosive clutches of oxidants that have been linked
with cancer in 57 out of 72 studies (The Santa Rosa Press
Democrat, February 17, 1999, page A6, reporting on a Harvard
Medical School study). For more on tomatoes see page 16.
But there's no one magic anti-cancer food or diet. Eating
to prevent breast cancer requires a balanced menu with
fiber, healthy fats, phytoestrogens and antioxidants, all
fresh and free of chemical additives.
Modifying the balance and type of estrogen, the female
sex hormone produced by the ovaries, offers an important
breast cancer safeguard. Fat cells, adrenal glands and,
before menopause, the ovaries, produce three "flavors" of
estrogen, the strongest of which, estradiol, is believed to
be carcinogenic when too plentiful or persistent in the
body.
Estrogen does its work by attaching to estrogen
receptors. Receptors are particularly numerous in the
epithelial cells that line milk sacs and ducts in the
breasts.
A receptor site is like a designated parking spot: Once
estrogen is parked there it triggers one of its 400
functions in the body, from preparation of the uterus for
pregnancy to intensifying nerve synapses in the brain.
The food we eat can be a source of estrogen; plant
estrogens, called phytoestrogens, are much weaker than the
body's estrogens, but they fit the same receptors.
Phytoestrogens exert a milder estrogenic effect than bodily
estrogen and are capable of blocking the more potent,
damaging versions.
Finding Phytoestrogens
Foods high in phytoestrogens include vegetables, soy,
flaxseed and herbs such as black cohosh, chasteberry, red
clover and turmeric. Soy is the darling of the day for good
reason. Both soy and flaxseed can lengthen periods, reducing
the body's overall exposure to estrogen.
Soy also contains genistein, an "isoflavone" very similar
in molecular form to estrogen but only 1/100,000 as potent.
Because of its structure, genistein can attach to cells just
as estrogen does; it also helps build carriers needed for
binding estrogen and removing it from the body (Journal of
Nutrition 125, no.3 [1995]:757S-770S). It acts as an
antioxidant to counteract free radicals.
Tumor Inhibition
Studies have demonstrated that genistein inhibits
angiogenesis (new tumor growth), slowing the progression of
existing cancer.
Soy is most protective for younger women. Postmenopausal
women benefit from soy's ability to diminish hot flashes and
for cardiovascular protection, especially in combination
with vitamin E, fiber and carotene (Contemporary OB/GYN,
September 1998, p57-58).
Experts don't know that much about the cumulative effect
of combining hormone replacement with soy, herbs and a diet
high in phytoestrogens. Menopausal women who boost their
estrogen this way should work with their health care
providers and monitor their hormonal levels every six to 12
months with salivary testing.
The Vegetable Cart
Some vegetables are particularly protective against breast
cancer because they change the way the body processes
estrogen. Indol-3-carbinol, found in the co-called
cruciferous vegetables such as cauliflower, broccoli and
cabbage, diminishes the potency of estrogen. (Broccoli also
contains isothiocyanates that trigger anti-carcinogenic
enzymes.) These vegetables supply fiber, beta-carotene,
vitamin C as well as other vitamins and minerals (Proc of
the National Academy of Science USA, 89:2399-2403, 1992).
Fiber from fruits, vegetables and whole grains reduces
insulin levels and suppresses the appetite by making make us
feel full, thus helping with weight control, so important to
resisting cancer. Fiber also helps build estrogen carriers
that keep unbound estrogen from being recirculated and
reattached to the breast receptors.
Cellulose, the fruit and vegetable fiber most binding
with estrogen, also rounds up free radicals that damage DNA
within cells.,p> Feeding the Immune System
Despite heightened public awareness and efforts to stick to
wholesome, healthful diets, experts increasingly link poor
nutrition to depressed immune systems. Many Americans are at
least marginally deficient in trace elements and vitamins
despite their best attempts to eat well; that's why a good
multivitamin/mineral is wise, even mandatory. Vitamins given
to people undergoing cancer treatment stimulate greater
response, fewer side effects, and increased survival
(International Journal of Integrative Medicine, vol. 1, no.
1, January/February 1999).
Nutrients tend to work synergistically on the immune
system. They should be taken in balanced proportions, and in
consultation with your health care provider.
Immune Boosters
n Research links low levels of calcium and vitamin D, an
inhibitor of cell division and growth, to higher breast
cancer rates.
n Riboflavin (B2), pyridoxine (B6), pantothenic acid
(B5), zinc and folate strengthen immunity. Selenium, in lab
culture and animal studies, has helped kill tumors and
protect normal tissues.
n Beta-carotene and vitamins A, E and C are antioxidants.
Vitamin C enhances vitamin E's effects, boosting immunity
and protecting against cell damage. The antioxidant
isoflavones in green tea, with soy, convey the anticancer
effects of the Asian diet. Research shows actions that
discourage tumors and gene mutations.
The food you eat influences hormones. Excess sugar raises
insulin, which acts as a growth factor for cancer and
interferes with vitamin C's stimulation of white blood
cells. It may contribute to obesity.
Alcohol is converted to acetaldehyde, which causes cancer
in laboratory animals. It affects gene regulation by
decreasing the body's ability to use folic acid. It
increases estrogen and the amount of free estradiol in the
blood. The liver damage that accompanies high alcohol
consumption frequently reduces its capacity to filter
carcinogenic products, regulate hormones and break down
estrogen. Studies of alcohol consumption have caused experts
to estimate that drinking more than two alcoholic beverages
a day increases breast cancer risk by 63% (OB-GYN News,
November 1, 1998, p. 12).
Fat Can be Phat
Fat conveys nutritional benefits. Not all fats are bad: we
can't survive for very long without certain fats. Fat can
turn you into a "well-oiled" machine. But the wrong kind of
fat (the fatty acids in red meats and fatty poultry) is
believed to be a major culprit in breast cancer.
Fat cells produce estrogen. Excess fat stores carcinogens
and limits carriers that can move estrogen out of your
system.
Once estrogen has attached itself to a receptor, the
health result depends on the type of fat in the breast.
Saturated fat, transfatty acids and omega-6 fat from
polyunsaturated vegetable oils such as safflower oil,
peanut, soybean oil, corn oil and in margarine can increase
the estrogen effect and trigger a powerful signal to the
breast cell to replicate.
Restraining Prostaglandins
Blood rich in the essential fatty acids omega-3 and omega-9
lowers cancer risk by driving down levels of prostaglandins,
which promote tumor growth. The blood and tumors of women
with breast cancer usually contain high levels of
prostaglandins.
Breast tissue is protected by omega-3 fat chiefly from
fish and flaxseed and by omega-9 from olive oil. Salmon once
a week or water packed tuna three times a week are
particularly beneficial. Fish oil supplements processed to
reduce contaminates are available. Cod liver oil isn't
recommended: its vitamin A and D levels are too high.
Flaxseed is the richest known plant source of omega-3.
Use a coffee grinder to benefit from the seed and oil for
the full estrogen effect; sprinkle ground flaxseed over
cereal or fold into baked goods. Drizzle flaxseed oil, found
in the refrigerator section of your health food store, over
salads or cereal. (Store the oil in the refrigerator.)
Olive oil, especially in the context of the so-called
Mediterranean diet of vegetables, omega-3-rich fish and
fresh fruit (Menopause Management, January-February 1999, p.
16-19), lowers the risk of breast cancer (The Lancet, May
18, 1996;347:1351-1356).
Selecting Organic Food
Select organic foods for extra anticancer protection.
Pesticides stimulate erratic cell action and often inhibit
the estrogen carrier's ability to attach and remove estrogen
from the body. Free floating estrogen then can attach to
breast receptors and cause trouble.
Buy or grow fresh, organic foods whenever you can. When
grilling meat, fish or poultry, reduce the area where
carcinogens may accumulate by trimming fat. Charred,
well-done meat is known to be carcinogenic. When grilling,
marinate meat first and reduce the cooking time on the grill
by slightly precooking.
Cancer prevention is an interlocking puzzle requiring the
limitation of fat consumption, weight control, exercise,
stress reduction and care for psychological and spiritual
balance. Possessing more cancer fighting pieces makes you
more likely to be able to complete the prevention picture.
Joseph L. Mayo, MD, FACOG and Mary Ann Mayo, MA, are the
authors of The Menopause manager: A Safe Path for a Natural
Change, an individualized program for managing menopause.
The book's advice, in easy-to-understand portions, isolates
in-depth explanations with unbiased reviews of conventional
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