Breast cancer is the most common cancer in the UK, with one in eight women developing the disease at some stage in their lifetime.1 This means over 50,000 women in the UK are diagnosed every year.
In May 2017 we published our latest Continuous Update Project (CUP) report on breast cancer, an analysis of the global scientific research into the links between diet, physical activity and weight and breast cancer.
Our report analysed 119 studies from around the world, including more than 12 million women and over 260,000 cases of breast cancer. The research found that different lifestyle factors affect our risk of pre-menopausal and post-menopausal breast cancers. Here, we discuss the key findings.
Drinking alcohol increases the risk of both pre- and post-menopausal breast cancer2
One potential reason for this is that alcohol is metabolised principally by the liver, but also in breast tissue, to acetaldehyde which is associated with DNA damage.
For cancer prevention, our recommendation is to not drink alcohol at all. Encourage people to limit alcoholic drinks to no more than 14 units a week, spread over at least three days.
Vigorous physical activity, such as jogging and cycling, lowers the risk of both pre- and post-menopausal breast cancer, whilst doing any type of physical activity lowers the risk of post-menopausal breast cancer
Among other factors, physical activity improves insulin sensitivity and reduces fasting insulin and C-peptide levels, a pattern associated with reduced cancer risk.
Encourage people to do at least 30 minutes of activity every day, such as brisk walking, gardening, swimming and dancing. Anything that makes them breathe a bit deeper counts.
Being overweight or obese throughout adulthood, and greater weight gain during adulthood, both increase the risk of post-menopausal breast cancer – the most common type of breast cancer, accounting for about 80 per cent of cases
Surprisingly, there is evidence that being overweight or obese in young adulthood, between the ages of around 18 to 30, actually decreases the risk of both pre- and post-menopausal breast cancer. In addition, being overweight or obese throughout adulthood decreases the risk of pre-menopausal breast cancer only. Scientists believe this is because overweight women will be exposed to different levels of hormones to lean women.
It’s important to remember that, as being overweight or obese increases the risk of ten other cancers as well as other diseases, it is not advised to be overweight.
Breastfeeding after having a baby is shown to decrease the risk of breast cancer
Breastfeeding induces a unique hormonal pattern along with an associated period of amenorrhea and infertility. This decreases lifetime exposure to menstrual cycles and therefore alters hormone levels, particularly androgens, which can influence cancer risk.
Encourage women to breastfeed exclusively for the first six months, if possible. Thereafter, they should provide nutritious complementary foods and can continue breastfeeding up to the age of two years or beyond.
- World Cancer Research Fund. Breast Cancer. 2017.
- World Cancer Research Fund International. Diet, Nutrition, Physical Activity and Breast Cancer (pdf). 2017.