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Pyruvate Kinase M2 (M2-PK), Stool

The M2-PK (Pyruvate Kinase M2) test is a new presymptomatic screening test for colon cancer. Until now, only non-specific tests for the presence of blood in the stool could be used as evidence of existing colon cancer or early-onset neoplasm. By measuring M2-PK in stool, it is possible to detect colon cancers that either bleed or not, as well as polyps, with high sensitivity (>85%) and specificity (>95%).

Cancer cells and polyps produce a special enzyme, pyruvate kinase M2 (PK-M2). This enzyme, M2-PK, is characteristic of all dividing cancer cells and generally of all rapidly dividing cells. If a tumor has formed, there will be an increase in the amount of M2-PK enzyme.

M2-PK measurement does not replace colonoscopy. The M2-PK test provides a comfortable and high-quality alternative to non-invasive tests such as fecal hemoglobin and as the first step in the early detection of colon cancer.

What are the advantages of the M2-PK test?

The main advantages of the M2-PK test are:

  • High sensitivity (>85%)
  • High specificity (>95%)
  • It does not depend on the presence of blood
  • Detects intestinal polyps with or without bleeding, especially polyps larger than 1 cm
  • Detects colon tumors with or without bleeding
  • It is not affected by the intake of certain foods
  • No special diet is required
  • It has no false-positive results due to hemorrhoids or other sources of blood in the gastrointestinal tract
  • Just a very small stool sample is enough
Who is the M2-PK test for?
  • In men and women older than 50 years
  • In men and women under the age of 50 with a risk factor, such as:
    • Presence of polyps or colon cancer
    • Women with a history of cancer of the uterus, ovaries, or breast
    • Family history of colon cancer
    • Patients with Crohn's disease and ulcerative colitis
    • Obesity
    • Alcohol and tobacco abuse
  • In men and women who for any reason do not decide or postpone a colonoscopy
More information on M2 Pyruvate Kinase (M2-PK)

The testing of M2 Pyruvate Kinase (M2-PK) in feces is used for checking for colon cancer. The presence of this enzyme in the stool is indicative of polyps in the colon and rectum, cancer of the colon and rectum, acute and chronic inflammatory intestinal diseases, and certain other diseases of the gastrointestinal tract.

The majority of tumors in humans produce in large quantities the oncogenic isoform (isoenzyme) M2 of an enzyme of the glycolytic pathway called Pyruvate Kinase (PK). This enzyme is responsible for the final stage of the glycolytic pathway (which begins with glucose substrate and ends with the production of pyruvate) and the production of energy for the cell in the form of ATP. Enzymatic characterization of a wide range of different tumors revealed that oncogenesis is accompanied by an increase in the total activity of the enzyme pyruvate kinase. It has also been shown that there is a shift towards the expression of pyruvate kinase (M2-PK) isoenzyme M2 and not of the other isoenzymes [the rest of isoenzymes are isoenzyme L (L-PK) in the liver and kidneys, isoenzyme M1 (M1-PK) in the muscles, heart and brain and the R (R-PK) isoenzyme in erythrocytes].

The M2-PK isoenzyme is released by cancer cells and can be detected in various body fluids. The concentration of the M2-PK isoenzyme in the blood is associated with tumor malignancy. In patients with adenomas or colon cancer, M2-PK is released into both the blood and feces. The increase in M2-PK in the blood was found in addition to gastrointestinal cancers and in a wide range of other tumors such as lung, kidney, breast, and cervical cancer.

Diagnostiki Athinon is the 1st laboratory in Greece that performs the M2-PK test.


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