Sitting Down for This? If You’re a Woman, You're Increasing Your Cancer Risk.

Women may have estrogen to thank, researchers say. (Photo: Getty Images)

You’ve heard it repeatedly: Sitting is the new smoking. But while experts agree we could all stand to get off our butts a little more, new research on the topic has a startling discovery: Women have a higher risk of developing cancer from sitting.

A study of 146,000 men and women published in the journal Cancer Epidemiology, Biomarkers & Prevention discovered that women who spend moreof their downtime sitting are at a 10 percent higher risk of developing cancer, specifically multiple myeloma, breast, and ovarian cancers.

Men, on the other hand, had no increased risk of developing cancer after sitting.

Study author Alpha Patel, PhD, strategic director at the American Cancer Society,tells Yahoo Health that she wasn’t shocked by her research’s finding that sitting may cause cancer since “there is a growing body of scientific evidence to suggest that sitting time may be associated with cancer and other disease risk.”

However, she’s a little stumped on why there’s a gender difference. Patel says it could be because she only studied how much people sat during their leisure time(i.e. not at work), or there may be a true biological reason.

This isn’t the first research that found women may be more at risk for developing cancer from sitting.

The American Cancer Society’s Cancer Prevention Study II discovered that women who sat for six or more hours a day had a 37 percent greater risk of death compared to those who sat for three hours or less a day. Butmen only had a 17 percent greater risk.

Related: The Two-Minute Solution to Sitting All Day

The disparity was even greater for those who didn’t exercise: Women who were inactive and sat for long periods of time were at a 94 percent higher risk of developing cancer, while men were at a 48 percent higher risk.

What’s going on here?

It may all be due to estrogen, says medical oncologist Homayoon Sanati, MD, medical director of the MemorialCare Breast Center at Orange Coast Memorial Medical Center in Fountain Valley, Calif.

He explains it this way to Yahoo Health: Ovarian and breast cancers are related to an increase in the production of estrogen. Sitting can increase the production of estrogen in a woman’s body through the development of extra fat cells that happen when a woman has a sedentary lifestyle.

Estrogen promotes the growth of breast and ovarian cells and, when more cells grow, there is an increased risk that those cells can have genomic errors that may lead to the development of cancer.

However, Sanati says men probably can’t become couch potatoes without consequences. “The study only looked at cancers diagnosed between 1992 and 2009,” he points out. “For men, prostate cancer may be diagnosed at the later stages of life.”

Research has repeatedly found a link between sitting and negative health consequences — for women and men.

An analysis of 47 studies published in the journal Annals of Internal Medicine in January found that people who sat for long periods of time were 24 percent more likely to die from health problems within 16 years.

But working out might not help: A 2010 study published in the journal Exercise and Sport Sciences Reviews discovered that physical activity alone may not be enough to off-set the negative health risks of sitting. And a 2011 study published in the journal Metabolism found that the body’s insulin response goes down after just one day of sitting, which can lead to the development of diabetes and other diseases.

Related: Sitting With Your Legs Crossed? 4 Reasons To Stop

Patel says that researchers still aren’t sure how much sitting is safe. “The evidence to date supports that sitting less (compared to more) is associated with lower risk of some types of cancer, cardiovascular disease, diabetes, and premature death from any cause,” she says. “However, the exact amount that is considered safe is still being studied.”

But Sanati says more movement seems to be better: “We know, for example,  that for women who have already had breast cancer, those who are involved in more physical activity have less of a chance of recurrence of the disease.”

He tells his patients that some sitting is fine, but to do it in moderation. And, if you have to sit for a long period of time, get up and walk for a few minutes after a half hour before sitting down again — it could save your life.

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