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M2-PK. New Screening Test for Colon Cancer

If the M2-PK test is negative then no further colonoscopy is needed.

Colon cancer is one of the most common cancers in the western world, which affects approximately 530.000 people annually in the United States and Europe, resulting in 255.000 deaths per year. In Greece, it is the 3rd most common cancer (after lung and breast cancer) with about 4.000 new cases and 2.500 deaths per year! However, early diagnosis of colon cancer is related to increased chances of a cure (almost 100%). Family predisposition, fatty foods, obesity, smoking, excessive alcohol consumption, lack of exercise, and age, are the most common risk factors for developing colon cancer.

The most reliable and effective method for colon cancer diagnosis is colonoscopy, which (should) be performed as a diagnostic test every ten years after the age of 55. In colonoscopy is examined the entire colon. During the colonoscopy, the doctor can see in detail the inside of the colon and take tissue samples for further analysis. If polyps are found, they can be removed immediately. Intestinal polyps (adenomas) are considered precursors to colon cancer. If there is a positive family history, i.e. if someone in the family has already been diagnosed with colon cancer, the colonoscopy should be done before the age of 50. However, the acceptance of this invasive method by the general population is low (and costly). For a successful colorectal cancer screening program, it is essential to use the next best screening tools, which should be easy, cost-effective, and well-accepted by patients. Patients identified with these tools should be further examined with the method of colonoscopy.

To date, the most commonly used screening test for the diagnosis of pre-symptomatic colon cancer is the search for fecal occult blood (fecal hemoglobin). Stool hemoglobin testing is a non-specific method for colon cancer diagnosis, given the fact that this test just recognizes the presence of blood in the stool. In addition, the test can only identify bleeding colon tumors. In the largest study on this subject, in which 2.885 participants underwent a total colonoscopy, the results showed that only 23.9% of participants with cancer had a positive stool hemoglobin test.

The M2-PK (M2 Pyruvate Kinase) test is a non-invasive screening method for the early detection of colorectal cancers and polyps. Until now, they have been used only non-specific tests, which detect the presence of blood in stool, as an indication of existing colorectal cancer. With the new M2-PK screening test in feces, it is possible to detect bleeding or not bleeding colon cancers, as well as polyps, with high sensitivity (> 85%) and specificity (> 95%). Cancer cells and polyps produce an enzyme in a specific form, the pyruvate kinase M2 (PK-M2). This M2-PK isoenzyme is the characteristic enzyme of all dividing cancer cells. When a tumor occurs, it is observed an increase in the concentration of M2-PK isoenzyme.

The main advantages of the M2-PK test are:

  • High sensitivity (> 85%)
  • High specificity (> 95%)
  • It does not depend on the presence of blood
  • It detects intestinal polyps with or without bleeding, especially polyps > 1 cm
  • It detects intestinal tumors with or without bleeding
  • It is not affected by the intake of specific foods
  • There is no requirement for a special diet
  • There is no chance of false-positive results due to the presence of hemorrhoids or other sources of blood in the gastrointestinal tract
  • A very small stool sample is enough


Diagnostiki Athinon is the first laboratory in Greece that perform the M2-PK screening test.


M2-PK flyer (in Greek)

Pyruvate Kinase (M2-PK), Stool


Uppara et al. World Journal of Surgical Oncology (2015) 13:48

Yong et al. Gut and Liver (2015), 9(5), 641-648

Sithambaram et al. PLoS ONE (2015), 10(7): e0131616. doi:10.1371/journal.pone.0131616

Tonus et al. World J Gastroenterol (2012), 18(30): 4004-4011

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