Another investigation in colorectal cancer screening is the occult blood test. With the help of the test even small - invisible to the eye - traces of hidden (occult) blood can be detected in the stool. Blood admixtures in the stool may be evidence of polyps or tumors. The test is obtained from the family doctor. Alternatively, one of the more recent immunological occult blood tests can be purchased at the pharmacy and sent to a laboratory for evaluation or even evaluated at home. The statutory health insurance pay the older, chemical Okkultbluttest the family doctor from the age of 50 years.
Stool tests: regular implementation important
Stool tests must be repeated every year and every positive result must be clarified by a colonoscopy. Since polyps and tumors do not bleed continuously but at uncertain intervals, stool tests can only find about 30 percent (in immunological stool tests, the detection rates are higher) of polyps or tumors. The test result of the chemical occult blood tests can also be falsified by certain foods.
A common stool test since 2002 is the tumor M2-PK test, which detects a tumor-specific enzyme in the stool instead of the blood and in this way discovers intestinal tumors that may be present. This test is available from the doctor or pharmacy. Scientific long-term studies on this test are not yet available.
Palpation of the rectum
Another method in the context of annual cancer screening is rectal palpation, in which the doctor scans the rectum with his finger to detect changes in the mucosa. However, this method alone is insufficient for colorectal cancer screening, because only tumors in the lower rectum can be detected and the rest of the colon and large intestine are not examined at all. Only a third of the tumors grow in the rectum and colon cancer increasingly occurs in the upper part of the colon.
Blood test by Septin 9 test
A new form of colorectal cancer screening is the Septin-9 blood test. If a colon tumor is present, altered genetic material is released into the blood in an early stadium, which can be detected by the Septin-9 blood test. Depending on the stage, the detection rate for this method is at least 67%, which is higher than for stool blood tests but lower than for colonoscopy.
The Septin-9 blood test does not require a previous diet or defecation, which requires little time. It can also be used in patients for whom a colonoscopy is not feasible. The Septin-9 blood test is not a cash benefit and is not yet offered by every practice, nor are there any longer-term studies available (February 2011).