He is leading the World Cancer Research Fund Global Cancer Update Programme, which performs evidence syntheses of the diet, adiposity and physical activity associations with risk of cancer development and survival.

He is a molecular epidemiologist with a strong focus on cancer aetiology and prevention. His research focuses on the role of genetic, dietary, metabolic and hormonal pathways in cancer development, prognosis and survival. He is further interested in evidence synthesis methods and applications, Mendelian randomization, pharmaco-epidemiology, and the methodological assessment and correction (via causal inference methods) of systematic errors in the biomedical literature.