Scientists have the first major evidence that blood tests called liquid biopsies hold promise for screening people for cancer. Hong Kong doctors tried it for a type of head and neck cancer, and boosted early detection and one measure of survival. The tests detect DNA that tumors shed into the blood. Some are used now…

Your speech may, um, help reveal if you’re uh … developing thinking problems. More pauses, filler words and other verbal changes might be an early sign of mental decline, which can lead to Alzheimer’s disease, a study suggests. Researchers had people describe a picture they were shown in taped sessions two years apart. Those with…