NASCAR Truck Series driver Bobby Hamilton announced Friday (March 17) he will discontinue racing after Friday's John Deere 200 at the Atlanta Motor Speedway. He was diagnosed with cancer in his neck about three weeks after the Daytona 500 race. Hamilton had a tumor removed Feb. 8 and will begin chemotherapy and radiation treatment at Vanderbilt University Hospital in his hometown of Nashville on Monday (March 20). In his absence, Hamilton's son, Bobby Jr., will drive the No. 18 Dodge.