Two cervical cancer cells divide in this image from a scanning electron microscope. Steve Gschmeissner/Getty Images/Science Photo Libra hide caption

itoggle caption Steve Gschmeissner/Getty Images/Science Photo Libra

Elizabeth, Samuel, Bryan and Noah Shaw amid Texas bluebonnets on Easter Sunday. Samuel was conceived with in vitro fertilization so he would not suffer from the hereditary cancer that afflicted Noah. Courtesy of Elizabeth Shaw hide caption

itoggle caption Courtesy of Elizabeth Shaw

TV host Samantha Harris says she will have a double mastectomy after being diagnosed with breast cancer. But the surgery doesn't eliminate cancer risk. Jordan Strauss/Invision/AP hide caption

itoggle caption Jordan Strauss/Invision/AP