The goal of this observational study is to learn about intestinal microbiome structure and function in individuals who have undergone a pancreatoduodenectomy and compare to healthy matched controls. The primary objectives of the study are: 1. To explore and describe any differences in the gut microbiota especially Shannon diversity index 2. To conduct functional profiling by exploring and describing any differences in functional metabolites produced in the gut in people having had pancreatoduodenectomy greater than 6 months ago compared to healthy matched controls. Participants will be asked to complete the following: * Three-day food, bowel and medication diary (see Protocol appendix 5) * Gastrointestinal Symptom Rating Scale (see Protocol appendix 6) * Quality of life questionnaire (see Protocol appendix 7) * Stool sample test using Microba Insight TradeMark (a small swab is taken from soiled toilet paper, sealed in a room-temperature storage capsule and mailed to the testing laboratory)