Dr. Nortin Hadler, author of Worried Sick: A Prescription for Health in an Overtreated America, writes occasional commentaries for ABC News online. In his most recent piece, published Friday, Hadler discusses the screening of health conditions that may — or may not — significantly affect your lifespan or your quality of life. He suggests you think twice before signing up for a PSA test, a colonoscopy, or a cholesterol check. In all cases, he says, you should definitely discuss it with your doctor. Dr. Hadler cautions, however, that sometimes the cure can be worse than the disease. Know your family history and discuss all the risks with your health care provider.