Overweight women who take regular intense exercise cut their risk of developing endometrial cancer, the most common form of womb cancer, by more than a third (39 per cent) , according to research published in the British Journal of Cancer today.
The study surveyed nearly 94,000 women aged 20 and over, including over 900 women who developd womb cancer, as part of the California Teachers Study. The research found that women with a high BMI over 25 – a measure of a person's shape based on their weight and height – who said they did at least three hours a week of strenuous exercise – such as a fast run or swim (making them very out of breath) – reduced their risk of developing the disease compared with women of the same weight who did half an hour or less a week.
The results of the survey, carried out by US scientists, showed that the protective effect came from exercise women had done from around a decade ago.
The women surveyed described the amount and intensity of exercise they did in the three years prior to the survey, and they were followed for up to 12 years after completing the survey. During the follow up period a total of 976 women (aged 67 years on average) were diagnosed with womb cancer.
Study author, Dr Christina Dieli-Conwright, at the University of Southern California, said: "Some previous studies have shown a reduced risk of womb cancer for women who are more physically active. But other studies have not shown a reduced risk.
"This important study supports existing evidence that suggests that taking up strenuous exercise could be a lifestyle change to help overweight and obese women reduce their risk of developing womb cancer."
Around 8,300 women in the UK are diagnosed with womb cancer each year with around 1,900 deaths each year.
Around 3,300 cases of cancer each year in the UK are linked to not doing enough physical activity and it's known to increase the risk of several different types of cancer including breast, bowel and womb cancer.
Sara Hiom, Cancer Research UK's director of patient engagement, said: "This new study adds to the existing evidence that being physically active can help to reduce the risk of developing womb cancer.
"Broadly it's a good idea to try being physically active and eat a healthy balanced diet with plenty of fruit, vegetables and fibre and cut back on alcohol, red or processed meat, saturated fat, and salt. Eating healthily and being active also work together to help you keep a healthy weight, but if you are very overweight it is wise to consult your doctor if you've not done intense exercise for some while. There's no 'anti-cancer' guarantee but these things can stack the odds in your favour."
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Dieli-Conwright C.M., et al. (2013). Long-term and baseline recreational physical activity and risk of endometrial cancer: the California Teachers Study, British Journal of Cancer, 109 (3) 761-768. DOI: 10.1038/bjc.2013.61