More than 41 million Americans need colorectal cancer screening

Study shows capacity exists to screen population within one year

More than 41 million Americans who are candidates for colorectal cancer screening have not been screened for this second-leading cancer killer, the first time the unscreened population has been quantified. According to a study published today in the American Gastroenterological Association (AGA) journal Gastroenterology, sufficient capacity exists to screen the unscreened population within one year using fecal occult blood testing (FOBT) followed by diagnostic colonoscopy for positive tests.

Guidelines of multiple agencies and professional societies underscore the importance of colorectal cancer screening for all individuals 50 years of age and older. Approved tests include barium enema, FOBT, flexible sigmoidoscopy and colonoscopy. Each screening option has advantages and disadvantages. “Given the enormous number of people who are eligible for screening but have not been screened, it is clear that regardless of the test, colorectal cancer screening is underutilized,” notes Bernard Levin, MD, AGA spokesperson. “Men and women who are otherwise fit should be screened for colorectal polyps and cancer because colorectal cancer can be prevented by polypectomy and cured when detected early.”

Researchers at the Centers for Disease Control and Prevention (CDC) used data from the U.S. Bureau of the Census and CDC’s National Health Interview Survey to estimate the size of the population that has not received colorectal cancer screening. In addition, a companion paper published in this issue of Gastroenterology reports findings of the CDC’s national Survey of Endoscopic Capacity which estimates the number of flexible sigmoidoscopies and colonoscopies performed in a year, and the maximum number that physicians could perform given an increased demand.

Although ample capacity exists for screening with FOBT, a test that is inexpensive and widely available, findings of this study suggest that capacity limitations exist for flexible sigmoidoscopy and colonoscopy. Limitations may be due, in large part, to the fact that only certain specialists are trained to perform colonoscopies and both tests tend to be more expensive than FOBT. Depending on the proportion of available capacity used for colorectal cancer screening in the United States, it could take up to 10 years to screen the unscreened population using colonoscopy alone, not taking into account the need for repeat screening tests or keeping the currently screened population up-to-date on screening.

“This is the first time that the size of the unscreened population has been measured, then compared to the number of tests being performed, to determine whether the public health community can meet the demand for widespread colorectal cancer screening,” said Laura C. Seeff, MD, lead study author with the CDC. “We hope these results will help shape colorectal cancer screening programs that may emerge in ensuing years.”

Routine screening tests can detect the large, more dangerous polyps, which can be removed during a colonoscopy. Guidelines published by the U.S. Multisociety Task Force on Colorectal Cancer in February 2003, recommend patients who have small polyps removed have follow-up or “surveillance” colonoscopies every five years. However, many patients are receiving surveillance colonoscopies more frequently, therefore reducing overall screening capacity. “Shifting colonoscopy resources away from excessive, unnecessary surveillance examinations could increase the available supply of screening colonoscopy,” notes Theodore R. Levin, MD, in an editorial accompanying the CDC study. Dr. Levin is the Regional Director of Colorectal Cancer Screening and a gastroenterologist at Kaiser Permanente, Northern California.

Since the study results are based on national data, results may not bear out in smaller geographic areas. Assessments are underway in 15 states to take into account differences in availability of screening methods and to further guide local planning for colorectal cancer screening. “These capacity estimates provide a foundation from which planning for widespread colorectal cancer screening and follow-up at the national and regional levels can occur,” said Seeff.