Molecular screening testing for colorectal cancer.

Worldwide, colorectal cancer is diagnosed in f1 million individuals each year, accounting for >9% of all new cancer cases (1). Approximately 529,000 people worldwide die of this disease annually. In 2006, it is estimated that 146,000 cases of colorectal cancer will occur in the United States with 55,000 deaths (2). Colorectal cancer is an excellent candidate for population-based screening because it is relatively common (5% lifetime risk in the United States). Most nonfamilial cases develop slowly over the years, and there are acceptable screening tests. Screening for colorectal cancer decreases both the mortality and the incidence and is recommended for those who are agesz50 years. Although interest in screening has increased, only 53% of the U.S. population who are ages z50 years have undergone screening (3). Currently available screening test options include fecal occult blood tests (guaiac or immunochemical methods), flexible sigmoidoscopy, colonoscopy, and double-contrast barium enema. Virtual colonoscopy (computerized tomographic and magnetic resonance colonoscopy) and molecular testing of stool and blood have recently been introduced and are still undergoing improvements and validation.