Actively prevent breast cancer
In western industrialized countries more and more women are getting breast cancer. It is not known exactly what the disease favors. A healthy lifestyle and diet play an important role in reducing the risk.
This is mainly due to improved early detection (see box) and treatment options. According to the Federal Statistical Office, breast cancer is the fifth leading cause of death with 3.9 percent, far behind cardiovascular diseases. The danger of breast cancer is not the regional growth in the breast, but that the tumor tends to scatter in the body. This can lead to secondary tumors, so-called metastases. These attack and destroy vital organs such as the brain, lungs, liver or skeleton.
Biggest risk: the age
Few realize that age is the biggest risk factor for breast cancer. While only one out of 200 women in the 50-year-olds is ill, it is about one in ten of the 80-year-olds. Most commonly breast cancer occurs between the ages of 45 and 65. But precursors are already available in younger years – usually between 35 and 45. Because the tumor needs from the first cell to a two-centimeter node between 5 and 15 years. The precursors are often very early (from a size of 5 millimeters) in the mammogram, a special chest X-ray, or ultrasound detect. The sooner doctors detect a tumor, the greater the chances of recovery. Unfortunately, the disease is now no longer a rarity in 30-year-old women. But then usually there is a hereditary predisposition.
Why breast cancer develops is not yet clear, and until today it can not be prevented. But there are several known factors that increase the likelihood of illness. Some risk factors can not be directly influenced. In addition to age and familial predisposition, these include a late first pregnancy (> 30 years) and an early first menstrual bleeding (<12 years) with menopause at the same time (> 55 years). Nevertheless, every woman can help reduce her personal risk. For much more than genetic predisposition, for example, an unhealthy lifestyle (lack of exercise, smoking, alcohol, etc.), environmental influences (environmental toxins, etc.), and improper nutrition favor the development of breast cancer. Experts discuss the influence of being overweight, Dietary fats, alcohol and phytochemicals. While the protective effect of regular exercise – no matter of what kind – has been adequately proven against breast cancer, the influence of dietary factors is still considered very controversial.
Overweight as a risk factor
Scientists are convinced that healthy eating can prevent one third of all cancer. Obesity plays a special role here. According to the latest estimates, a normal body weight would prevent 13,000 breast cancer cases each year. The question of how obesity plays a role in the risk of breast cancer has been the subject of many scientific studies – with very different results. For example, scientists found a link between overweight after menopause and breast cancer in the EPIC study (European Prospective Investigation into Cancer and Nutrition). In many other studies, however, there is only a weak or even no correlation in this regard. Much more pronounced seems to be the timing and extent of weight gain. For example, the risk of breast cancer increases by 40 percent if women grow from 10 to 15 kilograms after the age of 18 until postmenopause, that is, after menopause. With a weight gain of over 30 kilograms, the risk even doubles. However, these relationships are only found in women who did not take hormones for menopausal symptoms.
Surprisingly, some studies show that obesity before the menopause is associated with a lower risk of breast cancer. Experts suggest that heavier women have more irregular menstrual cycles and thereby circulate lower levels of estrogen. Low estrogen levels are associated with decreased breast cancer risk. The lower estrogen levels in overweight women seem to persist even after menopause. This mitigates the risk-increasing effect of the then increasing estrogen. It is also possible to explain why in many studies there is little or no correlation between postmenopausal overweight and breast cancer risk, but weight gain and breast cancer risk are much more strongly correlated. A Norwegian cohort study reveals another marker of breast cancer risk in overweight and obese post-menopausal women: HDL cholesterol. Women with a low HDL level are therefore three times more likely to have breast cancer than those with the highest levels.
Fats play a minor role
Whether the fat intake – regardless of obesity and total energy intake – increases the breast cancer rate remains questionable. The hypothesis is based primarily on the observation that national per capita consumption of fat correlates strongly with the mortality rate of breast cancer. However, studies in this regard conclude that fat weakly or not at all affects breast cancer rates, as opposed to energy. A study on young women reports a slight increase in breast cancer risk when eating high-fat meat in adolescence. Saturated fatty acids and animal fats can also increase the risk slightly. In another retrospective cohort study, the connection to the absolute amount of fat is missing. But the risk of breast cancer is decreasing,
Far more important than fat consumption seems to be the total energy intake. However, it is difficult to independently evaluate these two factors. Because fat is the highest in calories nutrient and thus contributes significantly to the Energie.Eine high energy intake in childhood accelerates the growth and the onset of menstruation (menarche) – a known risk factor for breast cancer. In addition, a high energy intake leads to weight gain in middle age and can thus also contribute significantly to the risk of breast cancer.
Carotenoids protect against breast cancer
Consuming fruits and vegetables lowers the risk of breast cancer. This is proven by a large number of case-control studies. A protective function of individual vitamins, secondary plant substances and minerals can only be detected for a few of these substances. Beta-carotene, lutein and zeaxanthin seem to be particularly effective. However, in the Nurses Health Study, such a relationship only occurs in pre-menopausal women and was most pronounced in hereditary pre-loading. In the two largest studies based on blood tests, women with low levels of beta-carotene and other carotenoids are at twice as likely to develop breast cancer risk as those with high levels.
Less breast cancer in sunny parts of the country
Folic acid had a protective effect on women who regularly drank alcohol and smoked heavily. For other vitamins or trace elements, no relationship to breast cancer or tumor growth can be detected. Another influence, however, seems to be the sunlight and thus the vitamin D production. Specific receptors for vitamin D were found in 73 percent of breast cancer cells. Activating them under laboratory conditions inhibits, among other things, the formation of new cells. In addition, epidemiological studies in the US and Russia have shown a lower breast cancer rate and better survival rates for women from sunny parts of the country compared to women from less sunny regions. Although the researchers have other influencing factors such as education, first and last menstrual period, body weight,
Benefits of phytoestrogens?
Phytoestrogens occur in different forms in different foods. Isoflavones are mainly found in soy products, lignans in flaxseed, whole grains and various fruits and vegetables. The body converts the plant hormones into either the anti-estrogen 2-hydroxyestrone or the estrogen-active and thus potentially harmful 16-a-hydroxyestrone.
Interestingly, studies in Japanese women and women who eat more broccoli or other vegetables are more likely to have elevated levels of antiestrogen. In breast cancer patients, on the other hand, the unfavorable estrogen derivative is increasingly present. Soya-derived phytoestrogens are being discussed as a cause of low breast cancer rates in high-soybean Asian countries. A recent study in Japan confirmed that women with the highest intake of isoflavones are at lower risk for breast cancer. Similar results are also shown with high or low consumption of miso soup, which is prepared from fermented soy paste. Flaxseed is also a valuable and seemingly even more effective source of phytoestrogens. Clinical studies have also shown that that isoflavones may exert an undesirable effect on the mammary tissue of pre- and post-menopausal women. It can therefore not be ruled out that high doses of phytoestrogens may be unfavorable in women with a genetic predisposition, in precancerous changes in the breast or in breast cancer. Women who consume more soy also have denser breast tissue, which in turn is considered a risk factor for breast cancer.
Beware of alcohol
There is a clear relationship between alcohol consumption and breast cancer risk. With a daily intake of 27 grams (equivalent to about 0.7 liters of beer or 0.3 liters of wine), the risk of abstinent women is already 40 percent higher, according to the largest case-control study. However, this only applies to pre-menopausal women. The higher the alcohol consumption, the higher the risk of breast cancer, is the conclusion of a meta-analysis of six studies. Other studies, however, showed a significant increase in risk only at more than 50 grams of alcohol per day.
Despite the many different outcomes, at least three diet-related risk factors are emerging right now: a high level of energy intake in childhood, a high weight gain in adulthood (according to research from age 18), and excessive alcohol consumption. But not all, to which certain risk factors apply, inevitably fall ill. Breast cancer develops from the complex interaction of many factors. Normal body weight and regular physical activity are the key to preventing exercise. Women who exercise for 30 minutes at least three times a week reduce their risk by 20-30 percent. Those who also feed on a large variety of fruits and vegetables from an early age onwards, prefer whole-grain products and vegetable fats and drink little alcohol, do a lot for