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June 3, 2015
Digest

Increased Physical Activity Associated with Lower Risk of 13 Types of Cancer

A new study of the relationship between physical activity and cancer has shown that greater levels of leisure-time physical activity were associated with a lower risk of developing 13 different types of cancer. The risk of developing 7 cancer types was 20 percent (or more) lower among the most active participants (90th percentile of activity) as compared with the least active participants (10th percentile of activity).

These findings, from researchers at NCI and the American Cancer Society, confirm and extend the evidence for a benefit of physical activity on cancer risk and support its role as a key component of population-wide cancer prevention and control efforts. The study, by NCI’s Dr. Steven C. Moore and colleagues, appeared May 16 in JAMA Internal Medicine.

Hundreds of previous studies have examined associations between physical activity and cancer risk and shown reduced risks for colon, breast and endometrial cancers; however, results have been inconclusive for most cancer types due to small numbers of participants in the studies. This new study pooled data on 1.44 million people, ages 19 to 98, from the United States and Europe, and was able to examine a broad range of cancers, including rare malignancies. Participants were followed for a median of 11 years during which 187,000 new cases of cancer occurred.

The investigators confirmed that leisure-time physical activity, as assessed by self-reported surveys, was associated with a lower risk of colon, breast and endometrial cancers. They also determined that leisure-time physical activity was associated with a lower risk of 10 additional cancers, with the greatest risk reductions for esophageal adenocarcinoma, liver cancer, cancer of the gastric cardia, kidney cancer and myeloid leukemia. Myeloma and cancers of the head and neck, rectum and bladder also showed reduced risks that were significant, but not as strong. Risk was reduced for lung cancer, but only for current and former smokers; the reasons for this are still being studied.

“Leisure-time physical activity is known to reduce risks of heart disease and risk of death from all causes, and our study demonstrates that it is also associated with lower risks of many types of cancer,” said Moore. “Furthermore, our results support that these associations are broadly generalizable to different populations, including people who are overweight or obese, or those with a history of smoking. Health care professionals counseling inactive adults should promote physical activity as a component of a healthy lifestyle and cancer prevention.”

NIH-Funded Study Reveals How Differences in Male, Female Brains Emerge

Male and female worms engage in different behaviors, which may result from sex-specific wiring patterns in the brain.
Male and female worms engage in different behaviors, which may result from sex-specific wiring patterns in the brain.

IMAGE: OLIVER HOBERT/COLUMBIA UNIVERSITY

Nematode worms may not be from Mars or Venus, but they do have sex-specific circuits in their brains that cause the males and females to act differently. According to new research published in Nature, scientists have determined how these sexually dimorphic (occurring in either males or females) connections arise in the worm nervous system. The research was funded by NINDS.

“For decades, there has been little focus on the impact of sex on many areas of biomedical research,” said Dr. Coryse St. Hillaire-Clarke, program officer on this NINDS project. “This study helps us understand how sex can influence brain connectivity.”

In nematode worms (known as Caenorhabditis elegans or C. elegans), a small number of neurons are found exclusively in male or female brains. The remaining neurons are found in both sexes, although their connection patterns are different in male and female brains. Dr. Oliver Hobert, professor of biological sciences at Columbia University, and his colleagues looked at how these wiring patterns form.

Hobert’s team observed that in the worms’ juvenile state, before they reach sexual maturity, their brain connections were in a hybrid, or mixed state, consisting of both male and female arrangements. As they reached sexual maturity, however, their brains underwent a pruning process, which got rid of particular connections and led to either male or female patterns.

“We found that differences in male and female brains develop from a ground state, which contains features of both sexes. From this developmental state, distinctly male or female features eventually emerge,” said Hobert.

Visual Impairment, Blindness Cases in U.S. Expected to Double by 2050

Findings suggest a need for increased screening to address treatable causes of vision loss. A slit lamp, with its high magnification, allows the eye care professional to examine the front of the patient’s eye.
Findings suggest a need for increased screening to address treatable causes of vision loss. A slit lamp, with its high magnification, allows the eye care professional to examine the front of the patient’s eye.

PHOTO: NEI

With the youngest of the baby boomers hitting 65 by 2029, the number of people with visual impairment or blindness in the United States is expected to double to more than 8 million by 2050, according to projections based on the most recent census data and from studies funded by NEI. Another 16.4 million Americans are expected to have difficulty seeing due to correctable refractive errors such as myopia (nearsightedness) or hyperopia (farsightedness) that can be fixed with glasses, contacts or surgery.

The researchers, led by Dr. Rohit Varma, director of the University of Southern California’s Roski Eye Institute, published their analysis May 19 in JAMA Ophthalmology. They estimate that 1 million Americans were legally blind (20/200 vision or worse) in 2015. Having 20/200 vision means that for clear vision, you would have to be 20 feet or closer to an object that a person with normal vision could see from 200 feet away.

Meanwhile, 3.2 million Americans had visual impairment in 2015—meaning they had 20/40 or worse vision with best possible correction. Another 8.2 million had vision problems due to uncorrected refractive error.

“These findings are an important forewarning of the magnitude of vision loss to come,” said NEI director Dr. Paul Sieving. “They suggest that there is a huge opportunity for screening efforts to identify people with correctable vision problems and early signs of eye diseases. Early detection and intervention—possibly as simple as prescribing corrective lenses—could go a long way toward preventing a significant proportion of avoidable vision loss.”

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