For as much as we know about breast cancer, we don’t know (yet) how to prevent it. According to the American Cancer Society (ACS), “lifestyle factors, such as reducing alcohol use, breastfeeding, engaging in regular physical activity, and staying at a healthy weight are all associated with lower risk.” And it’s the latter a new study published in BMJ Open took a closer look at.

Researchers culled data from nearly 93,000 women participating in the UK Collaborative Trial of Ovarian Cancer Screening in England, a study that aimed to see if two ovarian cancer tests were effective in detecting ovarian cancer in women early on. Each participant was over the age of 50, postmenopausal, and had no record of breast cancer during the study that took place between 2005 and 2010. Women who enrolled gave detailed information about their health (reproductive health and fertility), height, weight (BMI), family history of breast and ovarian cancer, as well as their use of contraceptives and, strangely enough, skirt size.

Over the course of the study, researchers continually sought out updates from participants, mainly pertaining to their health and lifestyle. And the results showed that “going up one skirt size every 10 years was associated with a 33 percent greater risk of developing breast cancer after the menopause; going up two skirt sizes in the same period was associated with a 77 percent greater risk.” In fact, skirt size was a stronger predictor for breast cancer than other influential factors, such as smoking and drinking.

“Convincing evidence is available that high-body weight, BMI, and adult weight gain, which typically reflect an increase in body fat, are associated with increased breast cancer risk,” the researchers wrote. “To the best of our knowledge, this is the first study investigating the association of waist changes using [skirt size] as a proxy and breast cancer risk. Between 20s and postmenopausal age, an increase in skirt size by one unit every decade increases the risk of postmenopausal breast cancer by 33 percent. Validation of these results could provide women with a simple and easy to understand message.”

The estimated amount of new breast cancer cases in the United States in 2014 is 232, 670 compared to the 50,285 cases in 2011 in the UK. Regardless of where you live, mitigating risk factors, such as weight gain, can reduce risk. The ACS reported nearly all breast cancers can be treated successfully if found early. Current guidelines calls for women age 40 and older to have a mammogram every year, with women in their 20s and 30s having a clinical breast exam by a health professional at least every three years. Additionally, women knowing how breasts normally look and feel can better indicate when theirs is cause for concern.

Source: Fourkala E, Burnell M, Cox C, Ryan A, Salter L, et al. “Association of skirt size and postmenopausal breast cancer risk in older women: a cohort study within the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS). BMJ Open. 2014.