When David Cook took the stage as grand marshal of Sunday’s Race for Hope 5K in Washington, D.C., it was with a heavy heart that he announced the passing of his oldest brother — and biggest fan — Adam, who lost his decade-long battle with brain cancer only the day before.

"I lost my brother yesterday… to a brain tumor," David told his fans after the race, which not coincidentally is a fundraiser to raise awareness and funds to fight brain tumors. "And I couldn’t imagine being anywhere else right now."

"I am consistently amazed at what survivors and the people in this audience do and go through," he continued. "It’s just amazing to me to see the resolve that survivors have. I lost one today… I lost one. But I gained 9,000. I will be here every year that they will have me."

<object width="320" height="265"><param name="movie" value="https://www.youtube.com/v/lmizGmyc6Hw&hl=en&fs=1&rel=0&color1=0xcc2550&color2=0xe87a9f"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="https://www.youtube.com/v/lmizGmyc6Hw&hl=en&fs=1&rel=0&color1=0xcc2550&color2=0xe87a9f" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="320" height="265"></embed></object>

Adam, 37, who was an attorney with a wife, Kendra, and two children, passed away on Saturday at his home in Terre Haute, Indiana. In April 2008, as David was singing his way to the top of the Idol charts, <a href="http://www.okmagazine.com/idol/view/5940/1/Cook%27s-Sick-Brother-Makes-It-to-Idol" target="_blank">Adam was able to make the trip</a> to cheer him on in one of the season’s most memorable moments.

Sound off in the comments below!

Join the conversation