Colorectal cancer (CRC) is the second most common cause of cancer-related deaths. Until now more than 230.000 people die of this disease within the european region. Although, CRC is curable if diagnosed early. A preventive screening on a regular basis is therefore of primordial importancel and should be an essential part of a general health check-up of people 50 years and older.
Concerning a preventive screening for CRC there is the possibility to regularly check the stool for occult blood. Furthermore, there is the possibility to carry out a colonoscopy that can be repeated after 10 years if the patient has been tested negative. Even though both screening methods have been proven to be very effective, the acceptance within the population is low. Reasons for the low acceptance are a dismissive attitude towards self-retrieved stool samples and towards colonoscopy. Therefore the Septin9-test offers a simple, non-invasive alternative for a preventive screening.
How does the test work?
In many diseases associated with tumors the methylation pattern of several genes can change. In colorectal cancer the Septin9 gene is methylated within a certain promotor region while it is not methylated in cells of the healthy intestinal mucosa.This methylated DNA can be detected by the Septin9 blood test. Only 1 blood draw is necessary.
How are the results of the Septin9 test interpreted?
A negative test result means that methylated Septin9-DNA could not be detected. So with this method, a CRC can be excluded. The negative predictive value of this test is 99,9%. That means that 999 of 1000 patients tested negative are correctly classified as being CRC negative (with an assumed CRC prevalence of 0,7%). A positive test result means that there is an increased likelihood for the presence of colorectal cancer. Since 45,7% of the patients tested positive are truly positve (positive predictive value) individuals with a positive test result are requested to undergo a colonoscopy for a definitive diagnosis.