Women who practise little or no physical activity are 71% more likely to suffer breast cancer, says research in Spain

Results of the study have been published in the US-based magazine Gynecologic, and feature 1,017 breast cancer patients aged 18 to 70, plus a healthy control group of the same size.

The Breast Cancer Research Group (GEICAM), made up of scientists from the two investigation centres, said pairs of women – one diagnosed with the disease and one without – of the same age and living in the same area were examined, and who had not genetic links to each other.

They were asked about the level of physical activity they undertook in their free time, including how many times a week they did so and for how long during the year before they had been diagnosed, in the case of the 1,017 cancer sufferers studied.

This way, scientists calculated the number of hours of metabolic effort per week for each patient and member of the control group to work out whether the amount of activity the women practised met with the World Health Organisation (WHO) recommendations of 150 minutes a week of moderate exercise.

Through this, investigators worked out an optimum physical activity level of at least 30 minutes of energetic walking per day.

After dividing up the women who reached at least this level of exercise, those who did some physical activity and a third group of those who lived a completely sedentary lifestyle, researchers discovered that the latter cluster were 71% more likely to suffer breast cancer.

Dr Marina Pollán, leading the study, said her team did not find any significant differences in the effect of exercise or its absence between the different tumour subtypes, although they did identify that the protection against breast cancer afforded by physical activity was greater in pre-menopausal women.

This protection level was also thought to be greater in women who have not had children, since maternity is thought to offer a small level of defence against breast cancer.

The research was carried out with a grant from the Scientific Foundation of Spain's largest cancer charity, the AECC; from the Beer and Health 2005 Foundation; the Spanish Medical Oncology Society (SEOM); the ministry for the economy, and the Spanish Breast Cancer Federation (FECMA).

Although research has long supported the benefits of regular physical exercise for health, never before has the real-life effect of its practice or absence on breast cancer in women of all ages been found.

This is also the first study which takes into account the presence or lack of the HER2 homone in the type of cancer suffered, and the effect of exercise on different subtypes of tumours.