Kaitlyn, daughter of U.S. Army 1st. Sgt. Stormy Knowles, plays in a gurney during the Parents and Children Fighting Cancer Holiday Party on Joint Base Andrews, Md., Dec. 13, 2014. Knowles’ son was diagnosed with acute lymphocytic leukemia in 2001 and received treatment through Walter Reed National Military Medical Center. (U.S. Air Force photo/ Senior Airman Nesha Humes)