ľ¹ÏÖ±²¥

Cancer is a genetic disease: it develops when genetic material (DNA) becomes damaged or changed, resulting in a loss of normal cellular growth controls. Some genetic alterations that can lead to cancer are inherited; others occur during a person’s lifetime due to exposure to chemicals (such as those in cigarette smoke), radiation, certain microbes, or other environmental factors.

Because cancer involves the interaction of multiple altered genes and proteins within cancerous cells, as well as within the cells of the surrounding normal tissue, a global approach is needed to capture the status of the 20,000 to 25,000 genes in the human genome. New technologies are allowing scientists to conduct genome-wide searches and look globally for all of the changes in genes or proteins that contribute to cancer's development and progression. These new approaches are sometimes referred to as genome-wide profiling, or genomic profiling.

The genomic information generated by NIH research projects, such as and , will allow the identification of the genetic changes that occur in several childhood cancers and 20 different adult cancers, including colorectal cancer. These programs are expected to fuel advances in:

• The development of new treatments or combinations treatments that target the specific alterations that allow cancer cells to grow and survive.
• The development of new screening methods that allow cancer to be detected and treated long before the onset of symptoms.
• The development of individualized cancer prevention strategies based on a person’s genetic makeup.

Preparing DNA for analysis.NIH

Understanding inherited traits that are associated with an increased risk of certain cancers is another area that scientists are exploring. NIH is funding several genome-wide association studies (GWAS) that examine the entire genome across specific populations to identify changes that are associated with disease risk.

To date, three GWAS studies in populations of European ancestry have found 11 genomic regions that are associated with a higher risk of colorectal cancer. The DNA changes in these regions may pinpoint genes that are involved in the development of colorectal cancer. Although further studies are needed, these findings have important implications for targeting high-risk individuals for colorectal cancer screening.