Biomarkers

A biomarker is a biologic specimen that may be a marker of exposure to some substance, of its metabolism, or of the integration of exposure and metabolism. Biomarkers may also reflect host characteristics. Because biomarkers are sometimes related to risk of disease, they are important in cancer control research.

One area of biomarker research that is garnering increased attention is nutritional biomarkers. Traditionally, self-report measures of dietary intake have served as the primary nutritional indicators, but biomarkers have several potential advantages. One is that they can capture dietary intake more objectively than can self-report measures. Another advantage is that nutritional biomarkers can indicate nutritional status, or the integration of intake and metabolism, which self-report of diet alone cannot do. However, they must be used judiciously, as there are several limitations as well. Nutritional biomarkers do not always correlate well with dietary intake assessments, biomarkers are not yet available for some dietary constituents, and variability in laboratory methods can affect comparisons across studies.

Surveillance of biomarkers is a new area of investigation at NCI. In particular, we're using large-scale studies of the US population to monitor nutritional biomarkers that are relevant to cancer. Work is focused on:

• understanding the relationship between various biomarkers and dietary intake estimates of food groups and nutrients;
• finding new biomarker profiles associated with dietary intakes or with medical conditions, such as insulin resistance; and
• evaluating nutrient-nutrient associations.