Breast cancer and sex hormones

Weight loss through diet and exercise may help overweight or obese post-menopausal women lower their levels of sex hormones associated with an increased risk of breast cancer, according to a new study published in the Journal of Clinical Oncology.

Dr Debra Larkins, Lead Physician for Bupa Health and Wellbeing, commented: “Researchers looked at the effects of following a healthy, balanced diet (between 1,200 and 2,000 calories per day), exercise (moderate to vigorous aerobic exercise for at least 45 minutes, five days a week) or a combination of both on sex hormone levels and other breast cancer biomarkers in overweight and obese post-menopausal women. They found that women who lost weight through diet or a combination of diet and exercise had much lower levels of sex hormones in their body after one year.

Post-menopausal women who are overweight or obese are known to be at an increased risk of developing breast cancer. This increase in risk may be caused by high levels of sex hormones, such as oestrogens and androgens, caused by excess body fat. This study suggests that by losing excess weight through diet or diet and exercise, a woman may be able to reduce her risk of breast cancer because she has reduced the amount of sex hormones in her body. However, the researchers haven’t given us the whole picture here because we don’t know if any of the women actually went on to develop breast cancer. None of the women were followed-up so, at the moment, it’s impossible to say if a reduction in sex hormones had any effect on the women’s risk of getting breast cancer.

Breast cancer is a complex disease that we still don’t yet fully understand. It’s very likely that it’s not caused by just one thing, but many lifestyle and genetic factors. If you’re trying to reduce your risk of breast cancer, don’t focus on just one particular change, such as losing weight, but try to take a more holistic approach to your health by giving up smoking, reducing the amount of alcohol you drink, eating less saturated fat in your diet and exercising regularly.

This study does prove one important point though, that it’s never too late to make lifestyle changes that can have a positive effect on your health; and if you’re overweight, losing weight can reduce your risk of long-term health problems, such as heart disease and diabetes.

Just under 440 post-menopausal women aged 50 to 75 took part in the year long study. All of the women had a body mass index of more than 25, meaning they were classed as overweight or obese, and did less than 100 minutes of exercise per week. At the start and the end of the study each woman had a blood test to measure their sex hormone levels and other breast cancer biomarkers. They also had their height, weight, body composition and fitness levels measured, as well as filling in a questionnaire about their medical history and lifestyle, and were given daily diet and fitness logs to complete.

Key facts

• Breast cancer is the most common cancer in women worldwide. It’s not always clear what the cause of breast cancer is but regularly checking your breasts for any changes is essential for detecting the disease early on.
• The menopause happens when a woman’s ovaries permanently stop producing eggs. Once a woman has gone through the menopause, she is no longer able to have children.
• The Department of Health recommend doing at least 150 minutes (two and a half hours) of moderate exercise over a week in bouts of 10 minutes or more.
• Generally, if you want to improve your diet there are certain foods you should aim to eat more of and others that you should eat less of. Eat more fruit and veg, fibre, low-fat dairy products and starchy foods, and eat less processed meat products, foods high in salt, sugary foods and drinks and high-fat foods.