1. Department of Urology, Royal Devon & Exeter Hospital, Exeter EX2 5DW, UK
2. University of Exeter Medical School, Exeter EX4 4QD, UK
3. Department of Pathology, Royal Devon & Exeter Hospital, Exeter EX2 5DW, UK
4. Department of Colorectal Surgery, Royal Devon & Exeter Hospital, Exeter EX2 5DW, UK