Doctors are much more capable of successfully treating many deadly diseases when they're detected early on, which is why routine preventive screening tests are critical. And certain tests are especially important for women. Mammograms, pap smears and colonoscopies have the potential to save millions of lives. But many women still don't know when they're supposed to start getting them or how often the tests are really needed. A colonoscopy picked up Cynthia Trogisch's stage three colon cancer. The 61-year-old teacher had never been screened before.