- more frequent testing
- that the patient collect the stool specimen
- follow-up colonoscopy when test results are positive.
Endoscopic and imaging tests detect polyps and early-stage treatable cancers; all require some degree of bowel preparation, and some require sedation. Testing intervals vary but, as a group, are longer than the interval between stool-based tests because polyps grow slowly. Because colonoscopy with biopsy is the preferred screening method for diagnosing CRC, it is the only screening option that also is a diagnostic procedure.
Where can screening guidelines be found?
Several professional organizations have developed guidelines for CRC screening. The 2 major
An update to both guidelines was released in 2008. Table 221,22 summarizes their recommendations.
Both guidelines recommend that screening begin at age 50 (Box). The primary differences between the 2 guidelines lie in the scope of recommended options for screening and the time frame for discontinuing screening:
- USPSTF requires a higher level of evidence for screening options and limits recommended options to FOBT, sigmoidoscopy combined with FOBT, and colonoscopy.
- ACS-MSTF-ACR emphasizes options that detect premalignant polyps, and generally is more inclusive of testing options; it also delineates tests as useful for either (1) early detection of cancer (stool-based studies) or (2) cancer prevention (endoscopic and imaging tests).
On the question of when to stop screening, ACS-MSTF-ACR bases its recommendations on life expectancy; USPSTF sets a specific age for ending screening.21,22
Recommendations of a third entity, the American College of Gastroenterology (ACG), are similar to those of ACS-MSTF-ACR; however, ACG (1) recommends beginning screening African American patients at age 45 because of their increased risk of CRC and (2) gives preference to colonoscopy as the preferred screening modality.23
Guidelines vary for high-risk patients (those with a history of familial adenomatous polyposis or another inherited syndrome associated with CRC; those with a family history of CRC in the young; those with a history of radiation exposure, history of CRC, or inflammatory bowel disease; and those with several first-degree relatives with CRC). Patients who fall into any of these categories should be referred for specialty care to establish the time of initial screening and the interval of subsequent screening.
CRC screening in the presence of psychiatric illness
Psychiatrists have an opportunity to support their patients when considering potentially confusing CRC screening recommendations. This opportunity might occur during a discussion about general preventive care, or a patient might come to an appointment after visiting a primary care provider, and ask for advice about screening options.
The potential benefits of CRC screening are negated if a patient is unable or unwilling to complete the test or undergo timely follow-up of positive results. It is important, therefore, to individualize screening recommendations—keeping in mind the degree of impairment from mental illness and the patient’s preferences and reliability to engage in follow-up. To date, there are no agreed-on screening guidelines specifically for patients with comorbid mental illness.
Adapting USPSTF guidelines for CRC screening of average-risk patients with mental illness, we offer the following recommendations:
Recommend screening. Begin routine screening at age 50. Patients with well-controlled or mild symptoms should be screened with a stool study with or without flexible sigmoidoscopy. Stool studies are safe, noninvasive, and require no bowel preparation; when used alone, however, they need to be performed yearly.
Screening accuracy is increased when a stool-based test is combined with flexible sigmoidoscopy; screening then can be performed less often. Unlike colonoscopy, flexible sigmoidoscopy does not involve sedation; a high-functioning patient might find this appealing and tolerate the greater frequency of screening. On the other hand, some patients might not accept the inconvenience of collecting the stool sample with the kit provided and returning it to the lab for processing.
Manage psychiatric illness optimally. For a patient with moderate or severe psychiatric symptoms, first attempt to optimize treatment of the underlying psychiatric condition before establishing a CRC screening program. If control of symptoms is likely to improve over the next 1 or 2 visits, it might be reasonable to defer screening until symptoms are better controlled and then reassess the patient before making specific screening recommendations. Screening should not be delayed, however, if significant improvement in symptoms is not expected in the near future. Lengthy delay might lead to failure in initiating screening at all.
We recommend that patients with persistent moderate or severe symptoms be screened with traditional colonoscopy. The sedation associated with colonoscopy (1) may be preferable to some patients with more severe illness and (2) allows for screening and diagnostic biopsy if needed during the same procedure. Screening with colonoscopy also: