Colorectal cancer (CRC) is the second leading cause of death from cancer in the
United States (Edwards et al., 2002). Research has shown that screening adults for early
cancers or their precursor lesions, followed by appropriate therapy and continued surveillance,
can reduce CRC incidence and mortality (Curry, 2003). A general consensus has
emerged that periodic screening of adults over age 50 is a valuable preventive intervention
and today most health plans cover CRC screening (United States General Accounting
Office, 2004). Yet, there is continued uncertainty about the specific screening strategies
that should be offered to individuals who are at average risk for CRC.
There are two reasons for the prevailing uncertainty about what screening strategies
make sense for these average-risk adults. First, the number of potential screening strategies
is large, encompassing not only the choice of technology (or technologies) but also
decisions about the age at which screening should begin, the frequency with which it
should occur, and the age at which routine screening should end. Several medical technologies
are available to detect early cancers or benign adenomas, the polyps that precede
most colorectal cancers. Those technologies vary widely both in cost and detection capabilities.
The list includes flexible sigmoidoscopy, colonoscopy, barium enema x-ray, and
fecal occult blood tests. The choices are growing, too. New technologies, including imaging
and molecular markers, are currently under development. Their entry will expand the
range of alternative screening strategies even further.