Screening carries risks
The choice about screening methods can be difficult; not all screening methods are beneficial, but many tests carry risks. Different screening methods have different risks or harms. Screening may make you anxious when you are considering or preparing for a test, or when a test result is positive. Before any screening, you may want to consult your doctor. It is important to know the risks of the test and whether there is evidence that it reduces the risk of death from cancer.
Consult your doctor about your risk of colorectal cancer and whether you need to be screened.
False-negative test results may occur
Even with colorectal cancer, screening results may be normal. A person with symptoms who has a false-negative test result (actually has cancer and the screening test shows no) may cause a delay in seeking medical care.
False-positive test results may occur
Even if you don’t have cancer, the screening result may show abnormal. False-positive test results (screening results that show cancer when there is none) can cause anxiety and the need for further testing (such as a biopsy), and additional testing is risky.
The following colorectal cancer screenings are risky:
Colonoscopy
Colonoscopy rarely has serious complications, but sometimes it can lead to tears and bleeding in the lining of the colon. These complications often occur with biopsy or polypectomy and can be serious and require hospitalization.
Sedation is used to reduce discomfort during microscopy. Sedation may cause cardiopulmonary problems, such as arrhythmia, heart failure, or dyspnea.
Sigmoidoscopy
Sigmoidoscopy has fewer complications than colonoscopy. Although lining tears and bleeding can occur, they are less common than with colonoscopy. Sigmoidoscopy usually does not require sedation, which can reduce the risk of complications.
Virtual colonoscopy
Virtual colonoscopy poses the least risk of physical injury compared with colonoscopy or sigmoidoscopy. The hazards of exposure to x-rays during virtual colonoscopy are not known. In addition to the colon, virtual colonoscopy often reveals problems in other organs, including the kidneys, chest, liver, ovaries, spleen and pancreas. These findings can lead to additional tests, such as colonoscopies, that may not improve the patient’s health.
Fecal occult blood test (FOBT) or fecal DNA testing
Failure to test for FOBT or DNA stool may be abnormal even if no cancer is found. Positive results may require additional testing, including colonoscopy.