4. Residence within the wider Washington D.C. area (approximately within a 120-mile radius from the NIH Bethesda campus) for the National Institutes of Health/US site and residents of the Kericho District Hospital catchment area, an approximate 93-mile (150 kilometers) radius, for the KEMRI/WRP CRC/Kenya site. Residence within the Bangkok Metropolitan area and nearby provinces are allowed to participate (approximately 120-mile radius from each of the clinical sites)