Article: Assessing and Minimizing the Risk of Breast Cancer

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Article: Assessing and Minimizing the Risk of Breast Cancer
Assessing and Minimizing the Risk of Breast Cancer

Patricia L. Morse
July 22, 2000

(Remember, what follows is the result of my search for answers as a HysterSister, not a medical professional)

ASSESSING RISK

Genetics

If any of the following are true for you, then you should have a conversation with your doctor about your risk of breast cancer: two or more close family members under 50 years of age who have had breast cancer, a family member with male breast cancer, one or more family members under 50 with breast cancer plus Ashkenazi ancestry, or ovarian cancer plus Ashkenazi ancestry. All of these are signs that you might have the BRCA1 or BRCA2 gene mutations. It's also important to look at the age at which your relative got breast cancer. The younger she was, the higher your risk. These specific genes may raise your risk of getting breast cancer by age 70 by as much as 56% and of getting ovarian cancer by as much as 16%. What's worse, women with the BRCA1 tend to have tumors that don't have progesterone receptors, which make them harder to treat. There are other, more indirect, influences that genes can have on cancer also. Still, only 5% of all breast cancers are related to the BRCA genes.

If you want to be tested for the BRCA gene, a list of places that do genetic testing and counseling is at http://cancernet.nci.nih.gov/genesrch.shtml or by phone from the Cancer Information Service at 1-800-4-CANCER.

Genes are not fate

A study just came out in the July 13, 2000, issue of the New England Journal of Medicine that looked at thousands of sets of twins in Scandinavia (the bigger the study, the better the data, usually). They concluded that most cancer risk, even for people with identical genes, comes from the environment and lifestyle. They said that genes probably explain 27% of the risk of breast cancer. So, you really can make a difference with exercise and diet. And, an oopherectomy (without HRT) apparently lowers the risk, even of the BRCA mutations, by 70%.

Reproductive History

If you were less than 12 when you had your first menstrual period, if your age at menopause was greater than 55, or if you had your first child after the age of 30 or you never had a child, then your risk is somewhat higher.

Benign breast disease

A breast biopsy that has any abnormal findings shows that your risk is higher. A breast biopsy that finds atypical hyperplasia shows a substantial increases. Most lumps, pain, or nipple discharge are benign, however, even if you do always have to check them out to be sure. For other information on benign breast disease, there's a basic fact sheet available from the American Academy of Family Physicians at http://www.aafp.org/afp/20000415/2385ph.html.

Age

The older you get, the more your risk increases and, oddly enough, so does your cure rate. In fact, it's so much less deadly in women over 70, that they have the same life expectancy as women without cancer at 70. It's harder to cure, though less likely, the younger you are.

Height

In a National Cancer Institute study, tall women were twice as likely to have breast cancer as the shortest women (still relatively low risks, but an increase nonetheless). The authors guessed that the extra hormones in adolescence had an influence.

Calculating Your Own Risk

The National Cancer Institute website has a program for calculating risk across a lot of variables. It's designed for doctors, but you can plug in your own information: http://cancertrials.nci.nih.gov/forms/CtRiskDisk.html

LOWERING THE RISK

Exercise

Exercise more than three times a week can reduce your risk of breast cancer by 30%-50%. This is the best thing you can do. One study of 25,624 pre- and post-menopausal Norwegian women across 14 years found that women who exercise vigorously for at least four hours a week had the lowest risk of breast cancer, regardless of other factors. It was particularly effective at lowering risk among lean women. This is one area where the studies all show the same thing. The more exercise, the lower your risk from estrogen-based cancer.

Lose Weight (or Better Yet, Don't Gain It)

Women 25 pounds or more overweight seem to get breast cancer more than twice as often as those who are not overweight. Women over 50 who gain 10 pounds after their 40s have triple the risk as thin women with a stable weight. A woman who is heavy in her 20s and 30s but loses weight by the time she reaches her 40s or 50s has the same risk as someone who never gained weight, while women who lose excess weight in the past 10 years reduce their breast cancer risk by 30%. So, it's better not to gain the weight, but losing it makes a big difference (easier said than done of course!). A diet lower in total calories was also good.at lowering risk aside from weight loss. Not only are women who are overweight more likely to get breast cancer, but they have a poorer prognosis, in part, perhaps, because it's caught later, sometimes because they avoid getting physical exams and mammograms.

Alcohol

Within 10 minutes of drinking a 3-4 oz glass of wine, estradiol levels in the blood are three times higher than normal levels. Even one drink a day increases risk by 9%. Five drinks a day, and your risk is as high as a woman with a family history of breast cancer. The American Cancer Society recommends that all women stay within a one drink a day limit, while those with a higher risk may want to avoid alcohol altogether. They don't ban alcohol because one drink a day seems to cause a 30%-40% drop in cardiovascular disease and a 20% drop in overall death rate. You might, however, get the same heart benefit from nonalcoholic grape juice without the increased risk of breast cancer.

Diet

Fruit and vegetables

What a surprise! A diet high in vegetables and fruits and low in animal fat lowers your risk. One analysis reviewed the results of 26 studies and concluded that the thing that made the biggest difference in all the studies was eating lots of vegetables. Fruit and vitamin C made some difference, but there was no doubt that people who ate the most vegetables, and a variety of vegetables at that, were helping themselves the most.

One of the keys seems to be folic acid. Folic acid is found in vegetables like collard greens, spinach, fava beans, chickpeas, lentils, split peas, and broccoli, but heat destroys 90% of it in food. So a combination of foods and supplements with folic acid might lower the risk of both breast and colon cancer. It's possible that lycopene, a chemical in tomatoes might play a role too in vegetables' good effect, though rats didn't do well on lycopene alone, so the jury's still out.

A review of 50 research studies concluded that fiber, even supplementary fiber, inhibits breast cancer growth. They don't know how because it doesn't seem to do it by lowering estrogen levels, but it definitely seems to work, making another argument for lots of vegetables and fruit. It's a win/win suggestion. Diets rich in fiber and vegetables and restricted in fat improve blood glucose, lower insulin, aid in weight control, and lower the risk of coronary heart disease, stroke, ocular macular degeneration, diverticulosis, and gallstones.

Meat

In addition to the saturated fat problem, there's a chance that charbroiled meat has a bad effect. One paper suggested that overcooking meat produces a precursor of testosterone, which boosts risk. Marinating meat first seemed to counteract the bad effect.

Soy

At this point, it's totally unclear what effect soy has on breast cancer. Do the phytoestrogens promote breast cancer? Maybe. Do they prevent it? Walter Willett, the chairman of the Department of Nutrition at the Harvard School of Public Health, thinks that the soybean protein with the isoflavones removed might be effective in preventing breast cancer growth. Another study suggested that it was the l-arginine in the protein that prevented hot flashes. So, the best approach to soy right now would seem to be taking it whole, as milk or tofu or soy nuts, and not just as isoflavones isolated in a pill.

Fat

The story of fat and breast cancer is the story of how science works: picking up a clue that there's a link, working to refine that link, being surprised by findings, and trying to find clues as to why the studies don't agree. What seems clear is that eating fat plays some kind of role in increasing risk. In some studies, when fat is reduced to 30% of total calories, breast cancer risk is lowered. An analysis of 13 studies showed that the greatest reduction of serum estradiol was when fat was reduced below 20% of calories. And yet, a look in 1992 at the fat intake/breast cancer connection in 88,795 women showed no difference in risk between those who ate 50% fat and those who ate 30% fat.

But the clues are starting to show up. The Mediterranean diet, for instance, has a high overall fat intake, but those countries have somewhat lower breast cancer. It seems that the difference is olive oil, which has a chemical called squalene that fights breast cancer cells in test tubes. A study of 61,000 Swedish women showed no correlation between total fat and breast cancer, but their fat comes from fish and the fat in fish is terrific for us. Saturated fat is bad. Polyunsaturated fat is bad. Transfat or hydrogenated oils are bad. Monounsaturated fat is good (the risk of breast cancer fell by 45% for every 10 g of monounsaturated fat in the diet), fatty fish like salmon is terrific. So, the breast cancer picture is looking like the heart disease picture--it's the type of fat that counts.

Tea

An interesting lead that they are pursuing is that any tea, but particularly green tea, seems to inhibit breast cancer tumors. And better yet is to drink milk in your tea like the British.

Kelp/Seaweed

And for those sushi and health food fans, a study in Japan found that watanabe seaweed (and perhaps other kinds of seaweed) inhibit at least one kind of breast cancer.

Supplements

Supplements so far are not panning out as having a direct effect on breast cancer risk, except for calcium and vitamin D. A look at over 80 different tests showed that calcium and vitamin D seem to play a role in preventing both breast and colon cancer. Vitamin D might also be linked with enhanced survival. Vitamin C and probably folic acid may do some good, but they do even more good if you get them from food. On the other hand, four long-term large-scale prospective trials of beta carotene, vitamin A, vitamin C, and vitamin E showed no effect on cancer risk. So it's better to improve your diet than to rely on pills.

Mammograms

Mammograms obviously don't lower the risk of getting breast cancer, but they do lower the risk of dying. It'a true that HRT does make breasts more dense. So women in natural menopause women using HRT are more likely to have false readings--positive or negative. This is probably true for surgical menopausal women on HRT too, though less so, since the total level of hormones is so much lower.

Self-exams

Many cancers are found through monthly breast self-exams, which find the typically hard, rough-edged, and immobile lumps. The combination of self-exam (or doctor's palpation), mammograms, and fine needle aspiration is 100% accurate when all three agree, so detection is improving all the time,with much earlier detection on the horizon.

Tamoxifen

In the spring of 2000, Tamoxifen was approved by the FDA for breast cancer prevention. It's for high risk women, such as women who've already had cancer. Tamoxifen apparently works by decreasing the uptake of estradiol into hormone-dependent mammary cancer cells. It fills the receptors so the estrogen can't get in. Between 1987 and 1997, breast cancer deaths among women younger than 70 dropped by 19% in the US and 22% in the UK, probably because of self-exam, mammography, earlier and better treatment, and the arrival of Tamoxifen. Some small European studies shed some doubt on Tamoxifen, but they've been called "not very well-designed."

It has some drawbacks. It doesn't help with the symptoms of menopause or heart disease, and it does have the serious side effects of venous thromboembolism, cataracts, and endometrial cancer. Raloxifen is another choice, but the studies are still underway to see how well it works against breast cancer..

SUMMARY

Here's a ranking of relative risks from the New England Journal of Medicine,

February 24, 2000, 342:564-571:

First degree relative with breast cancer 1.4-13.6

Age over 50 6.5

Breast biopsy with atypical hyperplasia 4.0-4.4

Age at first birth greater than 30 1.3-2.2

Age at menopause greater than 55 1.5-2.0

Breast biopsy with histologic finding 1.5-1.8

Age at first period less than 12 1.2-1.5

Hormone replacement therapy for natural menopause 1.0-1.5

Normal risk 0

The best ways to lower your risk are exercise three or four times a week, losing weight or maintaining a healthy weight, eat lots of vegetables and fruit, avoid saturated fat, use olive oil, eat fish, and take calcium and vitamin D (and maybe folic acid and vitamin C). And don't forget to do your monthly self-exam and get mammograms (if you're in your 40s or older).

If you want a copy of this article with all the (62 of them) references to medical articles, please email me at trish@hystersister.com.

This content was written by staff of HysterSisters.com by non-medical professionals based on discussions, resources and input from other patients for the purpose of patient-to-patient support.