His research interests are centered on early detection and prevention of colorectal cancer (CRC). He is a principal investigator in the PLCO cancer screening trial, a randomized trial of over 154,000 individuals which evaluated flexible sigmoidoscopy. He has used PLCO data to study surveillance colonoscopy utilization and yield, interval cancers, or cancers detected shortly after endoscopic procedures, and risk of colorectal cancer among subjects with a family history of cancer. Dr Schoen is the principal investigator, in collaboration with the Mayo Clinic in Minnesota, of a multicenter randomized immunotherapy trial, evaluating a vaccine for prevention of recurrent adenomatous polyps.