Former NFL tight end Greg Olsen announced the death of his older brother, Chris, in a poignant social media post. "It is with great sadness that I share this update. Despite fighting with every ounce of his being, my older brother Chris has lost his battle with Glioblastoma," Greg, 40, shared via Instagram on Thursday, February 5. "This terrible disease took many things, but it could never take Chris's spirit for life." Glioblastoma is an aggressive form of cancer that starts as a growth of cells in the brain or spinal cord.