Professor Thomas studied at Trinity College Cambridge and the London Hospital Medical College graduating in 1982. He trained at The London, Royal Free, St Mark's and St Mary's Hospitals. He was a Clinical Research Fellow at the Imperial Cancer Research Fund and wrote his PhD thesis on 'Molecular analysis of the Adenomatous Polyposis Coli gene region'. In 1994 he was appointed consultant physician and gastroenterologist at St Mary's and senior lecturer in the Imperial Cancer Research Fund Colorectal Cancer Unit at St Mark's. In 2007 he was appointed chair of gastrointestinal genetics at Imperial.
He heads the family cancer group at St Mark's which is now part of the CRUK Cancer Centre at Imperial. The aims of the group are to define the inherited predispositions to colorectal cancer and refine the management of familial risk.
His principal research interests are in the fields of:
Assessment of familial risk of colorectal cancer
Modification of familial risk by genetic testing
Colonoscopic surveillance for familial risk of colorectal cancer
Molecular genetic studies in familial colorectal cancer
Chemoprevention studies in familial colorectal cancer
He has long-standing collaborative research projects with Professor Peter Sasieni (Department of Epidemiology, Mathematics and Statistics, QMUL), Professor Ian Tomlinson (Welcome Trust Centre for Human Genetics, Oxford), Professor Sir John Burn (University of Newcastle) and Professor Hans Vasen (Netherlands Foundation for the Prevention of Inherited Tumours).
He is on the staff of King Edward VII Hospital (Sister Agnes) and is Head of HM Medical Household and Physician to the Queen.
et al., 2017, Urgent improvements needed to diagnose and manage Lynch syndrome, Bmj-british Medical Journal, Vol:356, ISSN:1756-1833
et al., 2015, Common colorectal cancer risk alleles contribute to the multiple colorectal adenoma phenotype, but do not influence colonic polyposis in FAP, European Journal of Human Genetics, Vol:23, ISSN:1018-4813, Pages:260-263
et al., 2015, Obesity, Aspirin, and Risk of Colorectal Cancer in Carriers of Hereditary Colorectal Cancer: A Prospective Investigation in the CAPP2 Study, Journal of Clinical Oncology, Vol:33, ISSN:0732-183X, Pages:3591-+
et al., 2015, Aberrant epithelial GREM1 expression initiates colonic tumorigenesis from cells outside the stem cell niche, Nature Medicine, Vol:21, ISSN:1078-8956, Pages:62-70
et al., 2014, A pooled analysis of the outcome of prospective colonoscopic surveillance for familial colorectal cancer, International Journal of Cancer, Vol:134, ISSN:0020-7136, Pages:939-947