By the time Alan Chrisman was diagnosed with stage 4 colorectal cancer, he was too sick to work. The cancer had spread to his lungs. His doctors said he may never get better. Chrisman, 59, applied for disability, the federal safety net program he contributed to with every paycheck during his 30 years working as a stonemason. But a doctor hired by Tennessee’s Disability Determination Services to review applications quickly concluded Chrisman wasn’t sick enough to get the $804 monthly benefit.