|Sarah McGowan-Freije, NatureCity author & contributor
Previous studies have shown that overall weight gain during adulthood is a risk factor for breast cancer. A recent study suggests that an increase in waist size is especially harmful. It found that going up a skirt size over a period of 10 years between your mid 20s and mid 50s is correlated with a 33% higher risk of developing breast cancer after menopause.
Participants in the study included 93,000 women who took part in the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) in England. All of the women were over 50, had already gone through menopause, and had no breast cancer when they started their time in the study between 2005 and 2010. They were mostly white, had a university education, and were overweight with a BMI of 25-26 at the beginning of of the study.
At the onset of the study, the women provided information on height and weight (BMI), reproductive health, fertility, family history of breast and ovarian cancer, use of hormonal birth control, and use of hormone replacement therapy (HRT). They also provided information about their current skirt size and what size they were in their twenties.
The researchers monitored the women for three to four years, at which point they asked again about whether or not they were continuing to use HRT, their general health, whether or not they’d been diagnosed with cancer, and lifestyle factors – including how much they smoked and drank.
During the study period, 1,090 of the women (a little over 1%) developed breast cancer. The researchers found that infertility treatment, family history of breast/ovarian cancer, and use of HRT were strongly associated with the risk of developing breast cancer. However, after controlling for all those factors, an increase in skirt size was found to be the strongest predictor of developing breast cancer.
The average skirt size for the women at age 25 was a US 8 and the average size at 64 was a US 10. Three out of four women had an increase in skirt size during the study period.
After analyzing the data, the researchers found that going up one skirt size every 10 years was associated with a 33% increased risk of developing breast cancer. Going up two sizes was associated with a 77% increased risk. The researchers estimated that a five-year absolute risk of postmenopausal breast cancer goes from 1 in 61 to 1 in 51 with every increase in skirt size over a 10 year period.
Researchers from University College London and the University of Manchester conducted the study. It was published on September 24, 2014, in BMJ Open.
The most dangerous kind of waist fat is the fat surrounding your internal organs, known as belly fat. Belly fat has been linked to a large range of health problems including insulin resistance, diabetes, cardiovascular disease and other obesity-associated health disorders.