Obesity and the rising incidence of certain cancers are the manifest expressions of problems with diet and lifestyle. A number of complex and closely inter-related factors mediate the association between environment and cancer development. This review seeks to summarise the current evidence pertaining to dietary factors and cancer incidence and progression. Relevant literature was identified by search of the Pubmed database using the terms: diet, cancer, carcinogenesis, tumourigenesis. References from relevant articles were searched. Selection of articles was based on peer review, journal and relevance. Where possible, meta-analyses of randomised controlled trials (RCTs) or large RCTs were cited preferentially. Variations in cancer trends between geographic regions and in migration studies point to the key role of environmental differences in cancer incidence. Mechanisms of tumorigenesis, including inflammation, angiogenesis, may be influenced by specific dietary constituents including glucosinolates, organosulphur compounds, genistein, curcumin, catechins, resveratrol and lycopene. Despite epidemiological evidence suggesting a link between dietary factors and cancer development, confounding factors such as obesity, physical activity and the sheer variety of bioactive compounds in a normal diet pose a great challenge to the study of mechanisms linking diet and cancer. A greater understanding of the interplay between dietary constituents and cancer development should un-cover new targets for the prevention and treatment of cancer.