Women who exercise moderately may be less likely than their inactive peers to develop breast cancer after menopause, according to a U.S. study.
Researchers, whose study was published in the journal Cancer, found that of more than 3,000 women with and without breast cancer, those who'd exercised during their childbearing years were less likely to develop the cancer after menopause.
The same was true when women took up exercise after menopause, said the group, led by Lauren McCullough at the University of North Carolina, Chapel Hill.
"What we can say is, exercise is good for you," McCullough said.
"It's never too late to start. Our evidence suggests that if you start after menopause, you can still help yourself."
The findings add to a number of past studies tying regular exercise to lower breast cancer rates. But all the studies only point to a correlation and don't prove that exercise itself is what reduces women's breast cancer risk.
There are reasons, though, to believe it can, said McCullough.
One possible way is indirectly, by cutting body fat, she said. Excess body fat is related to higher levels of certain hormones, including estrogen, as well as substances known as growth factors which can feed tumor development.
But exercise might also have direct effects by boosting the immune system or the body's ability to clear cell-damaging "free radicals."
In the study, which included 1,500 women with breast cancer and 1,550 cancer-free women of the same age, all were interviewed about their lifetime exercise habits and other lifestyle factors, like smoking and drinking.
The researchers found a connection between exercise and breast cancer risk only among women who had already gone through menopause.
Those who'd exercised for 10 to 19 hours a week in their "reproductive years" - the years between having their first child and going through menopause - were one-third less likely to have breast cancer than women who'd been sedentary during that time.
Women who'd started exercising after menopause also had a lower risk. If they averaged 9 to 17 hours a week, they were 30 percent less likely to have breast cancer than their inactive peers.
Of course, women who exercise can be different from sedentary women in many ways. So the researchers accounted for differences in education, income, smoking and certain other factors. Exercise was still linked to lower breast cancer risk.
Then the researchers took a closer look at body weight.
They found that among relatively lighter women, exercise was linked to lower breast cancer risks. And for obese women, it may have mitigated the increased breast cancer risk tied to their excess weight.
There was no link seen between exercise and breast cancer for the nearly 1,000 women in the study who developed breast cancer before menopause. That may be because beast cancer earlier in life has different causes.
The study had a number of limitations, including relying on women's memories of their exercise habits over a lifetime. In addition, any study like this can only look at broad patterns.
For now, McCullough said her findings support what's already recommended for good health - to get exercise. SOURCE: http://bit.ly/Mv5I72
City temperatures are forecast to shoot up in the coming years, exposing inhabitants to killer heat spikes, while rising sea levels and river flooding threaten homes, drinking water, and transport and electricity infrastructure.
The White House has said a decision will be announced before the G7 summit in Italy on May 26 and 27.
House Freedom Caucus says will back President Donald Trump's healthcare plans
The London-based Environmental Investigation Agency (EIA) estimated that in 2013, at least 93 percent of logging in Mozambique was illegal -- and that most of the illicit timber ended up sold in China.
Erik Solheim told AFP in an interview on Monday that even if the United States withdraws, China and the European Union will step in and take the lead to implement the global agreement on reducing greenhouse gas emissions.
Polyethylene represents 40 percent of Europe's demand for plastic products, mostly in the form of packaging and shopping bags.
The High Court had demanded ministers come up with a plan to tackle illegal levels of nitrogen dioxide pollution, largely caused by diesel emissions, by 3:00 pm (1400 GMT) on Monday.
PEG-2S promises to tackle superbugs that threaten world health
The change affects grazing conditions for the 146,000 or so semi-domesticated reindeer in Norway who feed on lichen and moss under the snow.
The discovery of the giant shipworm, a species never before studied, marked the first time scientists had live specimens in hand, according to an article published this week in American journal Proceedings of the National Academy of Sciences.
As many as one in 45 children are diagnosed with autism spectrum disorder in the United States, according to a recent study by the US Centers for Disease Control and Prevention.
A full 1.6 billion people remain affected by NTDs -- more than 500 million of them children -- but that number is down from more than two billion in 2010, WHO said.
For the first time ever in modern history, a team of scientists Monday documented as what they're describing as large-scale river reorganization as a result of human-caused climate change.
In the next few hours he will receive a healthy kidney thanks to a pioneering system that has made Spain the world leader in organ transplants for the past 25 years.
Japan's corals, the northernmost in the world, could offer important data to bolster knowledge about marine life, as Australia's Great Barrier Reef faces a threat to its survival.
China is the world's largest consumer and producer of tobacco, and the industry provides the government with colossal sums.