David Cook

David Cook's brother, Adam, lost his decade-long battle with cancer on Saturday. He was 37.

American Idol's Season 7 champ shared his loss on Sunday at the 12th annual Race for Hope 5K in Washington, D.C., where he was serving as grand marshal as well as participating.

"I actually lost my brother yesterday to a brain tumor, and I couldn't imagine being anywhere else right now," People quotes Cook as telling the crowd. Cook's team raised $98,000 at the event, which benefits brain cancer research.

Adam, despite battling cancer throughout his brother's Idol run, enjoyed at least one opportunity to see David perform in the Fox competition.

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