The multicenter team of researchers, led by Anne McTiernan, M.D., Ph.D., of Fred Hutchinson Cancer Research Center, found that women who had the lowest body-mass index, or BMI, and the highest physical-activity levels had the lowest levels of circulating estrogens, sex hormones that can fuel breast-cancer growth.
Specifically, they found a significant decrease in the two most common, biologically active forms of estrogen, estrone and estradiol, among the most active, lean women studied. The researchers found that women with high BMI and low physical-activity had mean estrogen concentrations that were 50 percent to 100 percent higher than that of women with low BMI and high activity levels.
"Women with high levels of estrogens have a two-to-four-times-higher risk of breast cancer than women with very low levels," said McTiernan, a member of the Hutchinson Center's Public Health Sciences Division and co-investigator of the Women's Health Initiative Clinical Coordinating Center, which is based at the Center. "If a woman can keep her own natural estrogens lower after menopause, it is probably going to be beneficial in terms of reducing her risk of breast cancer."
The study, based on a random sample of 267 postmenopausal women nationwide selected from the WHI Dietary Modification Trial, is the first of its kind to examine the dual impact of body weight and physical activity on levels of various circulating sex hormones thought to impact cancer risk.
"Other studies have looked at the impact of body weight by itself or physical activity by itself but this is the first to look at both together regarding their influence on hormone levels," McTiernan said. "This gives us a new understanding that combining weight control with high levels of physical activity is necessary for keeping estrogens at a healthy level in postmenopausal women." Exercising vigorously for 30 to 60 minutes a day, five days a week would achieve this benefit, McTiernan said.
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For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
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Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
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Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
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Let’s say the armrest is broken in your vintage car. As things stand, you would need a lot of luck and persistence to find the right spare part. But in the world of Industrie 4.0 and production with batch sizes of one, you can simply scan the armrest and print it out. This is made possible by the first ever 3D scanner capable of working autonomously and in real time. The autonomous scanning system will be on display at the Hannover Messe Preview on February 6 and at the Hannover Messe proper from April 23 to 27, 2018 (Hall 6, Booth A30).
Part of the charm of vintage cars is that they stopped making them long ago, so it is special when you do see one out on the roads. If something breaks or...
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