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A review of research has found no convincing evidence that selenium might lower the risk of cancer. The review of 55 studies was done by the Cochrane Library. This international group specializes in reviews of medical literature. In this case, the group looked at 49 “observational” studies. Mostly, they compared cancer levels in people who had more or less selenium in their blood. The review also looked at 6 studies that followed a design considered more likely to be accurate. These are called randomized trials. The studies took people who were similar and randomly divided them into groups. One group took selenium pills and another took a fake pill (placebo) or nothing. Then researchers kept track of people’s cancer levels over time. The observational studies found a slightly lower cancer risk linked to selenium. But the randomized trials found no link.

Many people with stable heart disease don’t get drugs that might prevent the need for a procedure to open their arteries, a new study finds. This pattern persists despite a landmark 2007 study. That study showed that taking three drugs could prevent heart attacks and deaths just as well as angioplasty. The drugs were aspirin, a beta-blocker and a statin. The study was expected to change medical practice. The new study looked at data on nearly half a million people. All had balloon angioplasty — with or without a stent — to open arteries near the heart. More than one-third of the cases occurred in the 18 months before the landmark study. The rest were in the 2 years after the study. Researchers looked at how many people were taking the recommended drugs when they came into the hospital for the procedure. Before the landmark study, 43.5% of the patients were taking all three drugs.

About 1 out of 7 strokes occurs during sleep, a new study suggests. In the United States, that would equal about 58,000 strokes a year. Most of these strokes can’t be treated with clot-dissolving medicines because no one knows when symptoms started. These medicines must be given within 3 hours of the first symptoms. The new study looked at records for 1,854 people who had an ischemic stroke. This is the type caused by blockage of blood flow to the brain. All of these patients were treated at hospitals in the Cincinnati area in 2005. Out of this group, 273 people showed the first symptoms of stroke when they woke up. In this situation, it’s always best to call 911, experts told HealthDay News and USA Today. Even if clot-dissolving drugs can’t be given, other treatments may help, they said. The journal Neurology published the study May 10.

Observing children in the emergency room for a while may reduce the need for computed tomography (CT) scans after a head injury, a new study concludes. CT scans use radiation. Repeated doses can increase the long-term risk of cancer, especially in children. Researchers looked at records on 40,000 children who had a minor head injury. All were treated in emergency departments. ER staff kept an eye on about 5,400 of the children for a few hours before deciding whether to do a CT scan. Of this group, 31% ended up getting a scan. The CT rate was 35% when doctors did not observe the child before deciding whether to do a CT. The rate of serious brain injury found was about the same in the two groups. Some children who did not get a CT scan at first did come back for one later. Only one serious brain injury was detected in these later tests.

Exercise boosts the risk of a heart-stopping problem, cardiac arrest. But if your heart stops in a place where people exercise, you’re more likely to survive than if you collapsed in another kind of public place. So says a new study presented at a conference. Researchers studied 960 cases of cardiac arrest. All of them took place in indoor public places. Of these cases, 150 occurred at places where people get exercise. These ranged from gyms to bowling alleys. People who had a cardiac arrest in an exercise facility were more likely to get CPR. About 77% received it, compared with 55% in other public places. About 16% were given a shock from an automated defibrillator machine. This is used to restart the heart. Only 7% got this treatment in other places. And more people survived a cardiac arrest in an exercise facility — 50% compared with 36% elsewhere.

Men under 65 who have early-stage prostate cancer are less likely to die of the disease if they have surgery right away, a long-term study finds. The study focused on about 700 men in Sweden. All were under age 75. The men were randomly divided into two groups. One group had surgery to remove the prostate. The other men had close follow-up by their doctors. They were treated if the cancer got worse. Researchers kept track of everyone for 15 years. In that time, 15% of the surgery group and 21% of the other group died of prostate cancer. Surgery saved 1 life for every 15 men treated. But only 7 men needed to be treated to save a life among men under 65. Study results may not apply to cancers diagnosed after a prostate-specific antigen (PSA) test. This is often what happens in the United States. But few of the Swedish men had this test.