Adam Cook, the oldest brother of American Idol seventh-season winner David Cook, died on Saturday after battling brain cancer for more than a decade.  He was 37.

The Idol champ revealed his brother's passing on Sunday morning at the 12th annual Cassidy & Pinkard Colliers National Race for Hope 5K in Washington, D.C., where he was serving as grand marshal.

"Like everybody here I'm affected by this disease.  I actually lost my brother yesterday to a brain tumor," said Cook, which brought gasps from the crowd.

Last month, Cook canceled two concerts on his current tour to attend to "personal family matters."  A rep for Cook subsequently told People that the reigning Idol champ had missed the tour dates to spend time with his brother.

Adam Cook made a memorable appearance during his younger brother's run to the Idol crown last spring when he traveled from his home in Terre Haute, IN to Hollywood to watch a performance episode taping as a member of the live studio audience.  At the time, Adam Cook was undergoing chemotherapy following his second diagnosis of brain cancer, which had spread to his spine.

He is survived by his wife Kendra and their two young children.

In addition to serving as grand marshal for the Race for Hope, Cook was part of a team that also raised $98,000 for the The Brain Tumor Society and Accelerate Brain Cancer Cure, two organizations that aid medical research on brain cancer.

"I couldn't imagine being anywhere else right now," Cook told the event's audience after revealing his brother had passed away.

"I go on stage every night and I make noise.  That's my job, and it's an amazing job, and I have everybody here who voted [for me on American Idol] to thank for that.  I am consistently amazed at what survivors like the people in this audience go and do... It's just amazing for me to see the results that survivors have.  I lost one today, but I gained 9,000.  I will be here every year that they will have me."
About The Author: Steven Rogers
Steven Rogers is a senior entertainment reporter for Reality TV World and been covering the reality TV genre for two decades.