Instructions for the colon screening test were devised so they can be understood in any language. Courtesy of Kaiser Permanente Center for Health Research hide caption

itoggle caption Courtesy of Kaiser Permanente Center for Health Research

Mammograms are a key screening tool for breast cancer. But critics say they're not good enough. Salih Dastan/iStockphoto hide caption

itoggle caption Salih Dastan/iStockphoto

Sally O'Neill decided to have a double mastectomy rather than "do a wait-and-see." Richard Knox/NPR hide caption

itoggle caption Richard Knox/NPR

Some images of lung cancer are clear cut. But in many others, a nodule on the screen turns out not to be cancer at all. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Doreen Ramogola-Masire, an obstetrician-gynecologist in Botswana, hopes that a simple, quick screen for cervical cancer with vinegar will catch the disease early and save women's lives. Jason Beaubien/NPR hide caption

itoggle caption Jason Beaubien/NPR

Before the colonoscopy begins, it pays to ask your doctor some pointed questions. Sebastian Schroeder/iStockphoto.com hide caption

itoggle caption Sebastian Schroeder/iStockphoto.com

Cells gathered during a Pap test. Those on the left are normal, and those on the right are infected with human papillomavirus. Ed Uthman/Wikimedia Commons hide caption

itoggle caption Ed Uthman/Wikimedia Commons