My current principal areas of research are: i) prostate cancer aetiology (with a focus on metabolic factors such as the IGF system), predicting its progression and secondary and tertiary prevention of the disease via population-based screening and low-toxicity nutritional and lifestyle interventions; ii) the short- and long-term child and adult health effects of breastfeeding and early growth; and iii) uncovering unexpected beneficial and adverse effects of commonly prescribed drugs through pharmaco-epidemiological studies based on automated clinical databases such as the UK GPRD. I am lead principal investigator (with Jenny Donovan, Freddie Hamdy and David Neal) on a population-based cluster randomised controlled trial of PSA testing for prostate cancer (the CAP trial) that involves over 410,000 UK men and co-principal investigator (with Mike Kramer and Emily Oken) on the long-term follow-up of a cluster randomised controlled trial of a breastfeeding promotion intervention that involves over 17,000 children in the Republic of Belarus (the PROBIT trial). I am lead principal investigator (with Professor Caroline Relton) on a £4.1 million CRUK programme grant in Integrative Cancer Epidemiology, combining genetic, metabolomic and epigenetic technologies to understand causal risk factors, mechanistic targets and predictive biomarkers in a variety of cancers.  In was co-PI with Dr Sarah Lewis on the WCRF funded project to develop systematic review methodology for mechanistic studies. I lead a cancer work-stream within the Bristol NIHR Biomedical Research Centre. I am interested in robustly assessing the causality of observational associations using instrumental variables analysis, working in collaboration with Frank Windmeijer, George Davey Smith, Tom Palmer and Neil Davies. With Willie Hamilton, Mike Stevens, Rachel Dommet and Theresa Redaniel, I have a developing interest in the presentation and diagnosis of childhood, teenage and young adult cancers in primary care.