Women can almost halve their risk of the disease after the age of 50, according to new research which identifies losing weight and taking up exercise as the big two postmenopausal strategies for tackling the cancer.
The researchers have calculated that just combining weight loss with exercising can lower the risk of the cancer that is newly diagnosed in around 46,000 women a year in the UK by more than a third,
‘Our findings suggest that a substantial proportion of postmenopausal breast cancer may be avoided by changes in lifestyle later in life,’’ say the researchers, whose study is based on more than 8,000 women, half of whom have been diagnosed with breast cancer.
Although a number of risk factors are known for breast cancer, many, like genes, height, age at first period and at menopause cannot be modified. Others like, alcohol and diet, which can be changed, have been linked to risk, but most research has centred on younger women.
In the new research, at three of the leading cancer treatment centres, including the Fred Hutchinson Cancer Research Center, Seattle, doctors looked at a range of risk factors and calculated a risk rate for each. The calculations were made by comparing data and lifestyle information on 3,499 women who had been diagnosed with the disease with that of a group of 4,213 healthy women of the same age.
The results show that 42.2 per cent of the risk of breast cancer is modifiable after menopause.
In contrast, there were a number of risk factors that could not be modified: women who were younger when their periods started, who were older at menopause, being older at their first full-term pregnancy and having had fewer children.
Length of oral contraceptive use and breastfeeding were not associated with breast cancer risk.
According to the Seattle researchers, this is the biggest risk that can be modified by post-menopausal women. They calculate that those of a healthy weight are 21.3 per cent less likely to develop breast cancer. A second study at Harvard University finds that losing 22 pounds after menopause reduces the risk of the disease by 57 per cent. Just how losing weight gives such a high degree of protection against breast cancer is not clear; one theory is that weight loss after the menopause lowers levels of oestrogen which is linked to the development of the cancer.
Starting exercising and doing it for five or more hours a week can lower the risk by 15.7 per cent. Exercises that the women in the studies started included jogging, running, cycling, aerobics, dance, swimming, walking and hiking. It's thought that exercise lowers risk of the cancer by reducing levels of body fat, which in turn lowers levels of cancer-promoting hormones.
Reducing alcohol consumption could lower the risk by 6.1 per cent. Just why alcohol increases the risk, is not clear, but there is some suggestion that the greater the consumption, the higher the blood levels of oestrogen.
Stopping using hormone use could lower the risk by 4.6 per cent.
Sun exposure may protect women from breast cancer, according to a Stanford University study which shows that women aged 35 to 79 with lighter skins who had higher sun exposure had almost half the risk of advanced breast cancer. Sunlight plays a vital role in the production of vitamin D in the body, and it's believed that the vitamin may have a role in stopping or slowing the growth of tumours, as well as boosting bones.
Eating a lot of sweet things, including biscuits, ice-cream, honey and chocolate may increase the risk of breast cancer. Researchers say that sweet foods are rich in several nutrients potentially involved in the development of breast cancer, including refined carbohydrates and saturated fats. The study, backed by the Italian League against Cancer, of women aged up to 74 found that the biggest sweet eaters had a 19 per cent increased risk. The researchers say the sweet foods may lead to insulin resistance. They also say insulin stimulates the production of hormones from the ovaries which have been linked to excess breast cancer risk.
While alcohol has been linked to an increased risk of cancer, regular drinking of wine may reduce the risk of breast malignancies. Women who have one glass a day have less than half the risk of developing the disease compared with non-drinkers, according to new research based on women with an average age of 58. Researchers at the Institut Universitaire de Recherche Clinique who carried out the study, described as the first to look at drinking patterns and breast cancer, say that antioxidants in wine may be protective.
A study based on 68,000 post-menopausal women found that those who regularly consumed dairy products had a lower risk of the disease. Women with the highest intake of calcium (more than 1,250 mg/day) had a 20 per cent less risk of the cancer than those consuming 500 mg/day. Two or more servings a day of dairy products led to a similar reduction. ‘Results support the hypothesis that dietary calcium and some other components in dairy products may modestly reduce risk of post-menopausal breast cancer,’ say the researchers from Atlanta, Georgia.