ScheBo M2-PK Test: Stool Screening for Colorectal Cancer

The ScheBo M2-PK test measures a tumor-related enzyme in stool and is used as a non-invasive aid in colorectal cancer screening. Unlike the classic fecal occult blood test, it does not depend on bleeding — which makes it a useful complement in laboratories and gastroenterology clinics. Here is what the test measures, how it works and how to use it correctly.

What is M2-PK?

Pyruvate kinase is a key enzyme in cell metabolism. Tumor cells shift to a special dimeric form of the M2 isoenzyme, known as Tumor M2-PK. It is not an organ-specific marker like PSA; it reflects the altered metabolism of tumor cells. When colorectal tumors or advanced polyps are present, Tumor M2-PK is released into the bowel and can be measured in stool.

What is the ScheBo test?

ScheBo Biotech (Germany) developed tests that use specific monoclonal antibodies to detect the dimeric Tumor M2-PK. The stool test is available as a quantitative ELISA for laboratories and as a rapid qualitative test. A plasma (EDTA) version is used in research and in follow-up of some cancers.

Why M2-PK and not only FOB?

• Independent of bleeding: many polyps and early tumors bleed only intermittently, so a blood-based stool test can miss them. M2-PK detects a metabolic marker, not blood.
• No diet restrictions: the result is not affected by meat or vitamin C intake.
• Complementary: combining M2-PK with an FOB test increases the chance of detecting colorectal lesions.

Understanding the result

• Negative: a colorectal tumor is less likely, but screening should be repeated at the recommended interval.
• Positive: requires further evaluation — usually a colonoscopy.

M2-PK may also be raised in inflammatory bowel disease and some gastrointestinal infections, so a positive result is not a diagnosis of cancer. In patients with suspected inflammation, fecal calprotectin helps distinguish inflammation from other causes. Always follow the package insert cut-off and the physician's interpretation.

Who should be tested?

• Adults in the age group recommended for colorectal cancer screening.
• People with a family history of colorectal cancer or polyps.
• Patients with unexplained changes in bowel habits, anemia or weight loss — as part of a medical evaluation.

Sample collection tips

• A small stool sample is enough; use the collection tube supplied with the kit.
• Avoid contamination with urine or toilet water.
• Deliver the sample to the lab within the time stated in the instructions.

Colorectal screening tests from Lab Solutions

Lab Solutions supplies stool-based screening tests for laboratories and clinics in Egypt, including the FOB rapid test, the FOB + Transferrin test and the Calprotectin rapid test. Browse our Oncology category or contact us for M2-PK availability and prices.

This article is for general information for healthcare professionals and does not replace medical diagnosis.