David Cook On Brother's Death: "I Ran As An Homage To Him."

American Idol winner David Cook said there were two factors in why he participated in Race For Hope-D.C., a brain cancer fundraiser Sunday after learning earlier that day of his brother's death.

"First, my brother never wanted his illness to affect others," Cook wrote on his website. "That was evident in the fact that he wanted his illness to have no part in my experience on Idol, a point he was quite adamant about. So, with that wish in mind, I ran and was involved with the event as an homage to him. Secondly, there are many people who are still battling, and by running and sharing my brother’s story, I hope that it offers those still fighting that much more resolve to not succumb to this wretched disease."

After a long bout with brain cancer, Adam Cook died at 37 early Sunday morning at a hospice in Terre Haute, IN.

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

Cook wrote that only tomorrow's show in Toledo, OH., was going to be canceled in the wake of his brother's passing.

A family friend told RadarOnline.com exclusively, "Adam passed away peacefully. He was surrounded by his family, including his wife Kendra, his children, his father and his step-mom, among others." (Photo: Splash News)