Catharine Becker of Fullerton, Calif., was diagnosed with stage 3 breast cancer at 43 despite having a clean mammogram. The mother of three didn't know she had dense breast tissue until after she was diagnosed. Heidi de Marco/Kaiser Health News hide caption

itoggle caption Heidi de Marco/Kaiser Health News

This spiral CT image of the chest shows a large malignant mass (purple) in one lung. A conventional chest X-ray could have missed this tumor, radiologists say. Medical Body Scans/Science Source hide caption

itoggle caption Medical Body Scans/Science Source

Some researchers recommend starting mammogram screening at age 40, while others say age 50. Some doctors think screening should be based on a woman's overall risk for breast cancer, not just her age. Hero Images/Corbis hide caption

itoggle caption Hero Images/Corbis

A kit with naloxone, also known by its brand name Narcan, is displayed at the South Jersey AIDS Alliance in Atlantic City. Naloxone counters an overdose with heroin or certain prescription painkillers by blocking the receptors these opioids bind to in the brain. Mel Evans/AP hide caption

itoggle caption Mel Evans/AP

For someone 2.5 inches shorter than average, the risk of coronary artery disease increases by about 13.5 percent, scientists found. PW Illustration/Ikon Images/Corbis hide caption

itoggle caption PW Illustration/Ikon Images/Corbis

You don't need to run a marathon — or wear a gorilla suit — to get a discount on John Hancock's new life insurance program. But at least one of them may help. Rick Rycroft/AP hide caption

itoggle caption Rick Rycroft/AP