4.
COLORECTAL CANCER SCREENING
Patricia Bellas, M.D.
For this chapter, we reviewed the recently published clinical guidelines for colorectal cancer screening, prepared by an AHCPR/American Gastroenterological Association expert panel (AGA Guidelines, 1997). In
addition, we reviewed the chapter on colorectal cancer screening in the second edition of the USPSTF Guide to Clinical Preventive Services (1996). Other
review articles on this subject published between 1993 and 1996 were obtained using a MELVYL search (Van Dam, 1995; Ferrante, 1996; Cohen, 1996). When
appropriate, original studies were reviewed (Winawer, 1993; Mandel, 1993; Selby, 1992; Muller, 1995; Newcomb, 1992; Bond, 1993; Kewenter, 1994; Ahlquist, 1993). In addition, we reviewed the chapter on laboratory screening
tests in Health Promotion and Disease Prevention in Clinical Practice (Woolf, 1996). Recently published articles were identified from other unpublished
reviews (Hardcastle, 1996; Kronborg, 1996; Allison, 1996; Rex, 1996; Read, 1997). Indicators for diagnosis, treatment, and follow-up of colorectal
cancer can be found in Chapter 5. IMPORTANCE Colorectal cancer (CRC) is the third most commonly diagnosed cancer with an annual incidence of about 140,000. It is the second most common cause of Incidence increases
cancer deaths, with about 55,000 deaths each year. significantly after age 50 and rises with age.
Estimated five year survival
is 91 percent for localized disease, 60 percent with regional spread, and six percent with distant metastasis. Unfortunately, 60 percent of patients with
CRC already have regional or distant spread at the time of diagnosis (USPSTF, 1996). Racial differences in survival have been documented, with lower
relative survival rates for African Americans than for whites.
57
SCREENING Risk Factors Persons considered at average risk for CRC comprise 75 percent of those with incident cancers. Those with one or more first degree relatives with CRC

下一页