The Science Behind Stool-Based DNA Screening

Over the past decade, intense research has shown the underlying basis of colorectal cancer to be an accumulation of genetic alterations. Approximately 75% to 85% of colorectal cancers are not inherited, but rather a disease of the genome, which means every cancerous cell has some genetic alteration. This knowledge of genomics forms the basis of this new method of colorectal cancer (CRC) screening. Known DNA alterations associated with screen relevant neoplasia can be identified.

For example, the Vimentin gene becomes methylated in 60-80% of colon cancers and exhibits equivalent sensitivity for early and late stage cancers. Mutation inactivation of tumor suppressor genes such as K-ras and APC are also known to play a key role in the development of colon cancer. By combining methylation markers, mutation markers and a fecal immunochemical test (FIT), Exact Sciences is developing a multiplex assay that is targeted to achieve at least 85% sensitivity for cancer, 50% sensitivity for pre-cancer with 90% specificity.