Your News Features on cancer (Nature 442, 735–743; 2006) highlight important developments in research since President Richard Nixon declared war on cancer in 1971. Numerous epidemiological as well as case-control studies have confirmed that early intervention translates into better survival.
However, when looking at biomarkers — DNA or proteins that could indicate pathological processes — it is important to distinguish between those that assess 'risk of cancer' and those that are suitable for screening. In the former, the individual may already be at risk, harbouring a pre-malignant condition such as adenomatous colonic polyps. Although benign, these polyps have the potential for malignant transformation over time. Screening, on the other hand, aims to detect disease in those who have no symptoms: the smear test, which picks up precancerous changes in the cervical lining, is a successful example.
The public needs to be aware of the differences, otherwise uptake will be low. This is a real problem with breast cancer, for example: uptake of screening is low among women from ethnic minorities, who consequently have higher-than-average rates of breast cancer in both the United Kingdom and the United States (V. N. Thomas et al. Int. J. Palliat. Nurs. 562, 564–571; 2005, and L. Jandorf et al. Cancer 107, 2043–2051; 2006).
Strategies for the prevention of cancer require biomarkers of early precancerous changes within normal tissue. Ideally, these should be linked to environmental factors that can be modified, such as diet. In colorectal cancer, for example — where 75% of variance can be explained by diet — the ideal biomarker should reflect differences in dietary exposure. Most people are interested in food and might be prepared to take the recommended action.
The successful test must not only be sensitive and specific for the disease but also appealing to the public; invasive procedures, for example, are less likely to win widespread acceptance. Lessons can be learnt from breast-cancer screening about improving education and awareness. Rightly or wrongly, the success of a screening biomarker is largely driven by public opinion, which is often poorly informed. Thus, the added task for scientists/clinicians is to convince the public of the efficacy and importance of any new biomarker.