Long-term weight gain has been linked to a 33% greater post-menopausal breast cancer risk, according to new research.
Weight gain has long been associated with cancer risks, but now research published in the online journal BMJ Open said that a thickening waist appeared to be particularly harmful.
Their findings are based on responses from 93,000 women over-50, who gave their current skirt size, and what their skirt size had been in their 20s, as well as detailed information on other factors which can influence cancer risk, such as reproductive health and family history.
Overall weight gain during adulthood is known to be a risk factor for breast cancer, but a thickening waist seems to be particularly harmful, indicating the importance of staving off a midriff bulge, the research shows.
Going up one skirt size every 10 years was associated with a 33 per cent greater risk of getting cancer after the menopause and going up two skirt sizes in the same timescales carried a 77 per cent greater risk.
The researchers estimate that the five year absolute risk of postmenopausal breast cancer rises from 1 in 61 to 1 in 51 with each increase in skirt size every 10 years. Adding BMI to the calculations did not significantly improve the prediction of risk.
As this is an observational study, no definitive conclusions can be drawn about cause and effect, and there is likely to have been some variation in skirt sizing over the years, say the researchers.
But an expanding waistline has been linked to other cancers, including those of the pancreas, lining of the womb, and ovaries, they point out, possibly because midriff fat is more harmful.
“Although the exact mechanism of these relationships need to be better understood, there is a suggestion that body fat around the waist is more metabolically active than adipose tissue elsewhere,” they write, adding that extra fat is known to boost levels of the female hormone oestrogen, on which many breast cancer cells rely for fuel.
Simon Vincent, Assistant Director of Research at Breakthrough Breast Cancer said: “We know that 40% of breast cancers could be prevented by changes to lifestyle such as being regularly active and maintaining a healthy weight. This study highlights an easy way to monitor your weight gain over time. Women are more likely to remember their skirt size when they were younger than their BMI.
“Here at Breakthrough Breast Cancer, we encourage all women to raise their pulse and reduce their risk. Women should take part in regular physical activity of moderate intensity for 3.5 hours per week. To learn more visit www.breakthrough.org/BRISK”.