Andy Lyon, an astrophysics student at UC Berkeley, was diagnosed with lymphoma in 2008. He went through chemotherapy, and returned to school, but his cancer returned. He did a stem cell transplant, but remission only lasted a few months. Faced with a now more limited range of options, he chose to forgo medical treatment and instead try and hike the entire 2,600 miles of the Pacific Crest Trail. His cancer returned in the form of a tumor on his spinal cord. He is off the trail and back in treatment. It may be hard for people without cancer to get why he'd make the decisions he did, but I get it. And I hope he's back on the trail soon. UPDATE: Oh hey, he's back on the trail. (thanks, Kit Mitchell)