An inexpensive vitamin can help reduce the occurrence of common skin cancers in people prone to that disease, researchers reported.

In a clinical trial, people who took two pills a day of nicotinamide, a form of vitamin B3 available as a supplement, had a 23 percent lower risk of developing non-melanoma skin cancer than those who took placebo pills.

"It's safe, it's almost obscenely inexpensive and it's widely available," Dr. Diona Damian, the lead investigator of the study, said in a news conference organized by the American Society of Clinical Oncology, who said the findings could be put into practice right away. However, Damian, a dermatology professor at the University of Sydney in Australia, said the vitamin should be used only by people who get frequent skin cancers, not by everyone.

THC doesn't help dementia patients

Pills containing an extract of marijuana do not significantly ease some of dementia's most difficult symptoms, including agitation, aggression and nighttime wandering, says the largest-ever study testing the safety and effectiveness of tetrahydrocannabinol, or THC, on elderly dementia patients.

The research — published in the journal Neurology — did offer some hope that marijuana might help this most vulnerable population: At the low doses tested, THC caused few notable side effects, suggesting that trials testing such medication at higher doses for dementia symptoms could safely move forward.

New era of genetic medicine

The federal government opened the door to a new era of genetic medicine by introducing a standard way to ensure the accuracy of DNA tests used to tailor treatments for individual patients.

The National Institute of Standards and Technology said that it had developed "reference materials" that could be used by labs to determine whether their machines were properly analyzing a person's genetic blueprint, or genome.

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