Taking exercise, even after the menopause, could cut women’s risk of breast cancer, but weight still matters.
We’ve heard, often, how important exercise is for our health. But how often do you need to do it, how hard must you exercise and for how long if you want to cut your cancer risk? A team led by Lauren McCullough at the University of North Carolina, Gillings School of Global Public Health looked at 1,504 women with breast cancer and 1,555 women who didn’t have the disease. The women covered a wide age range – from 20 to 98 years old – and were part of the Long Island Breast Cancer Study Project which is investigating possible environmental causes of breast cancer.
The results are encouraging for women of all ages, according to the study’s findings, published early online in CANCER, a journal of the American Cancer Society. Older and younger women – those who exercised before and during their postmenopausal years – had a lower risk of developing breast cancer. In fact the study says that these are the most critical years for reducing risk. And looking at all the women involved, from youngest to oldest, the study found that the most active had a 17% drop in risk compared with those who didn’t exercise.
“The observation of a reduced risk of breast cancer for women who engage in exercise after menopause is particularly encouraging given the late age of onset for breast cancer,” said Lauren McCullough. Breast cancer has been the most common cancer in the UK since 1997, and is more likely to affect older women. Between 2007 and 2009, 45% of breast cancer cases in the UK were diagnosed in women who were 65 and over.
There is one factor which is unchanged by being active: women who gained a significant amount of weight, especially after the menopause, had an increased risk of developing breast cancer, even if they exercised. This comes alongside the news from Cancer Research UK that even when overweight Britons know that their weight increases their risk of cancer, they struggle to summon the willpower to lose weight.
Being overweight or obese is one of the most important avoidable cancer risks. Scientists have estimated that the number of people who are overweight or obese in the UK could lead to around 19,000 cases of cancer a year.
Dr Harpal Kumar, Cancer Research UK’s chief executive, said: “Unless we tackle the obesity epidemic in the UK we risk cancer cases soaring. We understand that it can be extremely hard for people to maintain a healthy weight but keeping those extra pounds at bay would ultimately save your life.”
Sarah Williams, health information officer at Cancer Research UK, has reservations about the exercise study from North Carolina. This is because, rather than measuring things directly, the researchers asked women to remember how much exercise they had done outside work for every decade of their lives since their 20s, as well as how much they had weighed.
“There’s a substantial amount of evidence that breast cancer is less common among women who are more physically active. But just how active women need to be to reduce their risk is not yet clear,” she says. “While more research is being carried out, we recommend that women aim to do at least 30 minutes of exercise, five days a week, which will also help with keeping a healthy weight. Cutting down on alcohol and saturated fat can also reduce the risk of developing breast cancer.”