MONDAY, Feb. 25 (HealthDay News) -- A special technique that uses laser light to sample a person’s breath can detect molecules that may be markers for a number of diseases, a U.S. study says. This approach, called cavity-enhanced direct optical frequency comb spectroscopy, may one day help doctors screen patients for diseases such as asthma, cancer, kidney failure and diabetes, according to the team of scientists at JILA, a joint institute of the National Institute of Standards and Technology and the University of Colorado at Boulder.