David Cook: "I Lost My Brother To A Brain Tumor"

American Idol winner David Cook choked back tears Sunday morning as he revealed that his beloved older brother Adam had died of brain cancer at the age of 36.

Cook made the announcement during a heartfelt speech at the 12th annual Race For Hope event in Washington, D.C., an event that raises money for brain cancer research.

When Cook was first introduced, the crowd -- not knowing his brother had passed away -- greeted the singer with cheers and appaulse. Cook even began his speech by making a joke about coming to the race to get a tan , but then a couple of minutes into his talk, the crowd gasped when Cook revealed his brother had just died.

Cook told the crowd he couldn't imagine being anywhere else now.