[Faecal pyruvate kinase type M2--a valid screening parameter for colorectal cancer? Preliminary results from a multicenter comparative study]

Comparison of faecal protein biomarkers' diagnostic accuracy for colorectal advanced neoplasms: a systematic review and meta-analysis

Early diagnosis of colorectal advanced neoplasms (ANs), including colorectal cancer (CRC) and advanced adenoma (AA), has a positive effect on the survival rate. As a first attempt, the aim of this meta-analysis was to compare the diagnostic accuracy of faecal protein biomarkers for the detection of colorectal neoplasms with consideration of a wide range of covariates. A systematic literature search was performed up to Jun 10, 2021 on Web of Sciences, Scopus and PubMed. The diagnostic accuracies were calculated using the bivariate/hierarchical random effect model. Biomarkers were determined to be clinically applicable (CA) if they had areas under the curve > 0.70 and positive and negative likelihood ratios > 2 and < 0.5, respectively. A total of 47,059 test results were extracted from 16 immunochemical faecal occult blood test (iFOBT), 26 pyruvate kinase-M2 (PK-M2) and 23 faecal calprotectin (FC) studies. Only iFOBT, PK-M2 and FC for CRC plus iFOBT and PK-M2 for AN were CA. iFOBT had significantly superior accuracy (P = 0.02 versus PK-M2 and P < 0.01 versus FC for CRC; P < 0.01 versus PK-M2 for AN). Regarding covariates, the lateral flow method of PK-M2 measurement increased its accuracy for CRC detection compared to the enzyme-linked immunosorbent assay (P < 0.01). iFOBT is recommended as the most accurate faecal biomarker for CRC and AN diagnosis.

KRAS Mutations and M2PK Upregulation in Stool Samples from Individuals with Positive Fecal Occult Blood Tests Screened for Colorectal Cancer

Background

Screening for colorectal cancer (CRC) requires non-invasive methods of high diagnostic sensitivity and specificity. We evaluated the measurement of genetic and protein biomarkers of CRC in stool samples with the aim of testing their clinical utility in a CRC screening program.

Patients and Methods

Individuals aged 53–75 years who were at risk of CRC and immunochemical fecal occult blood test (iFOBT) positive were invited to submit stool samples for molecular testing prior to colonoscopy. KRAS codon 12 Gly→Asp, Gly, Val, and codon 13 Gly→Cys gene mutations were tested using an in-house real-time ARMS PCR method. M2PK levels in stool samples were measured utilizing a commercial ELISA kit.

Results

At colonoscopy, 7.6% of patients were found to have CRC, 50% had adenomas, 10.6% had hyperplastic polyps, 20.2% had diverticulosis and hemorrhoids, and 11.6% had normal mucosa. The best sensitivity for CRC (50%) was found in those cases where M2PK and KRAS abnormalities coexisted. M2PK showed a detection rate of 40.3% for adenomas but the combination of M2PK and KRAS abnormalities was found in only 5.7% of adenomas (P <0.01). iFOBT was false positive in 31.8% of cases in which colonoscopy excluded neoplastic lesions, while the coexistence of molecular and enzymatic abnormalities was more specific with false positive rates between 8.3% and 9.0% (P <0.05).

Conclusion

Our molecular screening approach demonstrates that detection of cancer-associated biomarkers measured in iFOBT-positive stool samples could help separate true from false positives in a FOBT-based screening process. M2PK showed particular promise for the detection of CRC and adenomas.

Colorectal Cancer Screening: Stool DNA and Other Noninvasive Modalities

Colorectal cancer screening dates to the discovery of pre-cancerous adenomatous tissue. Screening modalities and guidelines directed at prevention and early detection have evolved and resulted in a significant decrease in the prevalence and mortality of colorectal cancer via direct visualization or using specific markers. Despite continued efforts and an overall reduction in deaths attributed to colorectal cancer over the last 25 years, colorectal cancer remains one of the most common causes of malignancy-associated deaths. In attempt to further reduce the prevalence of colorectal cancer and associated deaths, continued improvement in screening quality and adherence remains key. Noninvasive screening modalities are actively being explored. Identification of specific genetic alterations in the adenoma-cancer sequence allow for the study and development of noninvasive screening modalities beyond guaiac-based fecal occult blood testing which target specific alterations or a panel of alterations. The stool DNA test is the first noninvasive screening tool that targets both human hemoglobin and specific genetic alterations. In this review we discuss stool DNA and other commercially available noninvasive colorectal cancer screening modalities in addition to other targets which previously have been or are currently under study.

The Diagnostic Accuracy of the M2 Pyruvate Kinase Quick Stool Test--A Rapid Office Based Assay Test for the Detection of Colorectal Cancer

Background

M2 pyruvate kinase (M2PK) is an oncoprotein secreted by colorectal cancers in stools. This the first report on the accuracy of a rapid stool test in the detection of colorectal cancer (CRC).

Objective

To determine the sensitivity, specificity and positive and negative predictive value of a rapid, point of care stool test M2 PK- the M2PK Quick.

Methods

Consecutive cases of endoscopically diagnosed and histological proven CRC were recruited. Stools were collected by patients and tested with the immunochromatographic M2PK Quick Test (Schebo Biotech AC, Giessen, Germany). Controls were consecutively chosen from patients without any significant colorectal or gastrointestinal disease undergoing colonoscopy. CRC was staged according to the AJCC staging manual (7^th Edition) and location of tumor defined as proximal or distal.

Results

The sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy were: 93%, 97.5%, 94.9%, 96.5% and 96.0% respectively. The positive predictive value for proximal tumors was significantly lower compared to distal tumors. No differences were seen between the different stages of the tumor.

Conclusions

The M2-PK Quick, rapid, point-of-care test is a highly accurate test in the detection of CRC. It is easy and convenient to perform and a useful diagnostic test for the detection of CRC in a clinical practice setting.

Faecal pyruvate kinase isoenzyme type M2 for colorectal cancer screening: A meta-analysis

AIM: To present a critical discussion of the efficacy of the faecal pyruvate kinase isoenzyme type M2 (faecal M2-PK) test for colorectal cancer (CRC) screening based on the currently available studies.

METHODS: A literature search in PubMed and Embase was conducted using the following search terms: fecal Tumor M2-PK, faecal Tumour M2-PK, fecal M2-PK, faecal M2-PK, fecal pyruvate kinase, faecal pyruvate kinase, pyruvate kinase stool and M2-PK stool.

RESULTS: Stool samples from 704 patients with CRC and from 11 412 healthy subjects have been investigated for faecal M2-PK concentrations in seventeen independent studies. The mean faecal M2-PK sensitivity was 80.3%; the specificity was 95.2%. Four studies compared faecal M2-PK head-to-head with guaiac-based faecal occult blood test (gFOBT). Faecal M2-PK demonstrated a sensitivity of 81.1%, whereas the gFOBT detected only 36.9% of the CRCs. Eight independent studies investigated the sensitivity of faecal M2-PK for adenoma (n = 554), with the following sensitivities: adenoma < 1 cm in diameter: 25%; adenoma > 1 cm: 44%; adenoma of unspecified diameter: 51%. In a direct comparison with gFOBT of adenoma > 1 cm in diameter, 47% tested positive with the faecal M2-PK test, whereas the gFOBT detected only 27%.

CONCLUSION: We recommend faecal M2-PK as a routine test for CRC screening. Faecal M2-PK closes a gap in clinical practice because it detects bleeding and non-bleeding tumors and adenoma with high sensitivity and specificity.

New faecal tests in gastroenterology

Most abdominal disorders present with a limited number of overlapping symptoms. Blood tests are not routinely available for use in diagnosis and so investigation tends to require complex imaging procedures or endoscopy and biopsy. These are invasive for the patient, may be associated with morbidity and mortality and have considerable resource implications. Biochemical tests on a single sample of faeces are therefore a valuable alternative. Measurement of faecal calprotectin has been shown to have a role in the diagnosis of inflammatory bowel disease and in its monitoring. Lactoferrin is also of benefit used in this way. Faecal elastase has been demonstrated to be of use in the diagnosis of pancreatic insufficiency. A number of faecal markers have been explored in colorectal cancer. Faecal occult blood testing is used for population screening, but the metabolomic marker tumour, M2-pyruvate kinase, has potential for use in both diagnosis and screening. DNA testing has advantages in colorectal cancer but the exact applications of such tests require further evaluation.

Tumor M2 pyruvate kinase: a tumor marker and its clinical application in gastrointestinal malignancy

Proliferating cells, in particular tumor cells, express a dimeric isoenzyme of pyruvate kinase, termed Tumor M2 pyruvate kinase. In the last few years, much attention has been paid to this novel tumor marker that can be determined in EDTA-plasma and in the feces. It has been used in diagnosis and surveillance of a variety of malignant diseases. As compared with the established tumor markers, Tumor M2-PK in EDTA-plasma proves to have at least equal sensitivity in pancreatic, gastric, esophageal, colorectal and cholangiocellular cancer. In combination with established tumor markers, EDTA-plasma M2-PK is a useful tool in diagnosis and surveillance of gastrointestinal tumors. In colorectal cancer, M2-PK in EDTA-plasma even proves superiority as compared with CEA. Fecal Tumor M2-PK testing resembles a good noninvasive screening parameter for colorectal cancer with a reported sensitivity of 68.8-91.0% and a specificity of 71.9-100%. It is superior to fecal occult blood testing in colorectal cancer screening. Since it is effective, easy to handle and bears rather low costs, fecal Tumor M2-PK testing is recommended for large-scale CRC screening.

Comparison of an established simple office-based immunological FOBT with fecal tumor pyruvate kinase type M2 (M2-PK) for colorectal cancer screening: prospective multicenter study

OBJECTIVES

The immunological fecal occult blood test (IFOBT) has established itself as a more precise marker for colorectal cancer (CRC) screening than traditional guaiac-based FOBT. The simpler, cheaper, and more convenient newer office-based IFOBTs have been validated for diagnosing CRC. Dimeric isoenzyme of pyruvate kinase, M2-PK, expressed by tumor cells, has as well been proposed as a screening tool for CRC. This is the first study comparing fecal M2-PK as a screening biomarker for CRC against previously evaluated office-based IFOBT and colonoscopy.

METHODS

Six hundred forty consecutive subjects (symptomatic, as well as for CRC screening) referred for colonoscopy for various indications across five centers in Germany provided the stool samples for performing M2-PK and an immunochemical FOB strip test. The IFOBT used was a rapid immunochromatographic assay for detection of fecal hemoglobin. For M2-PK, a commercially available sandwich enzyme-linked immunosorbent assay (ELISA) was used. The M2-PK test needs 6 h, while the office-based test can be read in just 10 min and is five times cheaper.

RESULTS

Office-based IFOBT had sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive and negative likelihood ratios (LR) of 64.5, 96.3, 72.0, 94.9, 17.5, and 0.4 for diagnosing colorectal neoplasia (CRN), while the above performance characteristics for M2-PK at a cutoff value of 4 U/mL were 72.4, 73.8, 29.0, 94.8, 2.8, and 0.8 respectively.

CONCLUSIONS

This office-based IFOBT was found to have significantly higher specificity, PPV, and positive LR as compared with M2-PK. IFOBT proved to be a convenient, noncumbersome, quick, and cheap tool in patients with above-average risk for detection of CRN.

Nicht-invasive Diagnostik kolorektaler Tumore – Hat der Guaiac-Test ausgedient? / Non-invasive detection of colorectal cancer – do we still need the guaiac-based fecal occult blood test?

Aufgrund der leichten Handhabung und des Nachweises einer Mortalitätssenkung gilt der Nachweis von okkultem Blut (FOBT) im Stuhl derzeit als das am weitesten verbreitete Screeningverfahren für das kolorektale Karzinom. Als nachteilig erweisen sich allerdings eine unzureichende Sensitivität, insbesondere beim Nachweis früher Stadien und eine nach wie vor geringe Akzeptanz in der Bevölkerung. Vorläufige Daten zum Nachweis von Calprotectin oder der Tumor-M2-PK im Stuhl ließen bessere Screeningeigenschaften erwarten. Aber auch hier schränkt die geringe Sensitivität für frühe Vorstufen und unzureichende Spezifität mit zu erwartenden hohen Folgekosten die Tauglichkeit der Tests deutlich ein. Die kürzlich entwickelten immunologischen FOBTs (I-FOBT) erweisen sich als spezifischer und sensitiver. Sie beruhen auf dem Nachweis von humanem Hämoglobin mittels spezifischer Antikörper und sind somit unabhängig von diätetischen oder medikamentösen Faktoren, was zu einer deutlich besseren Akzeptanz führt. Sie gelten derzeit als kosteneffektivste Verfahren unter den nichtinvasiven Screeningmaßnahmen. Der Nachweis von Tumor-DNA im Stuhl eröffnet eine neue Ära zum frühzeitigen Nachweis kolorektaler Karzinome. Erste kleinere Studien weisen auf eine sehr gute Sensitivität dieser Verfahren hin. Sie lagen für kolorektale Karzinome zwischen 62–91% und für Adenome zwischen 26–73% bei mit 93–100% sehr guter Spezifität. Als nachteilig im Vergleich zu den derzeit verfügbaren Screeningtests erweisen sich allerdings die vergleichsweise hohen Kosten.

Value of fecal tumor M2 pyruvate kinase in diagnosis of colorectal cancer

AIM: To evaluate the value of fecal M₂ pyruvate kinase (M₂-PK) as a screening biomarker for colorectal cancer.

METHODS: The tumor fecal M₂-PK was determined by enzyme-linked immunosorbent assay (ELISA) in colorectal cancer patients (n = 80) and healthy controls (n = 80), and the results were comparatively analyzed.

RESULTS: The cut-off value to discriminate patients from controls was established at 166.7 mkat/L for tumor M₂-PK. The mean level of fecal tumor M₂-PK was significantly higher in colorectal cancer patients than that in the normal controls (713.41 mkat/L vs 59.55 mkat/L, P < 0.0001), and the overall sensitivity and specificity were 77.5% and 92.5%, respectively. With the progression of colorectal carcinoma, the level of tumor M2-PK as well as the sensitivity was increased (F = 52.984, P < 0.0001). In patients with Dukes A (n = 11), B (n = 37), C (n = 25), and D (n = 7) stages, the mean levels of tumor M₂-PK were 233.53, 522.58, 847.27 and 1998.04 mkat/L, respectively, and the sensitivities were 63.64%, 75.68%, 84% and 84%, respectively.

CONCLUSION: Tumor M₂-PK is detectable in the feces of colorectal cancer patients and correlated with the staging and metastasis of the carcinoma, and it can help to make early diagnosis of colorectal cancer in patients with sub-clinical symptoms.

Colorectal cancer screening by non-invasive metabolic biomarker fecal tumor M2-PK

AIM: To evaluate the utility of the innovative fecal tumor M2-Pyruvate kinase (M2-PK) test in our daily clinical routine, as a marker for the pre-selection of patients who should subsequently undergo colonoscopy for the diagnosis or exclusion of colorectal cancer.

METHODS: Fecal tumor M2-PK was measured in stool samples of 96 study participants (33 patients with colorectal cancer, 21 patients with rectal carcinoma and 42 controls) who all underwent total colonoscopy.

RESULTS: In 39 of 42 individuals in the control group, fecal tumor M2-PK was below 4.0 kU/L (93% specificity). Colorectal tumors were accompanied by a highly significant increase (P < 0.001) in fecal tumor M2-PK levels (median: colon carcinoma, 23.1 kU/L; rectal carcinoma, 6.9 kU/L; colorectal carcinoma, 14.7 kU/L), which correlated with Duke’s staging and T-classification. The overall sensitivity was 78% for colorectal cancer, increasing from 60% for stage T1 to 100% for stage T4 and from 60% for Duke’s A to 90% for Duke’s D tumors.

CONCLUSION: Fecal tumor M2-PK is an appropriately sensitive tool to pre-select those patients requiring colonoscopy for the further diagnostic confirmation or exclusion of colorectal cancer.

Prospective multicenter evaluation of fecal tumor pyruvate kinase type M2 (M2-PK) as a screening biomarker for colorectal neoplasia

Proliferating cells, particularly the tumor cells, express a dimeric isoenzyme of pyruvate kinase, termed M2-PK. It's a direct target of several oncoproteins; the determination of fecal tumor pyruvate kinase type M2 (M2-PK) might be another promising tool for colorectal cancer (CRC) screening. In this study, we have evaluated fecal M2-PK as a screening biomarker for colorectal neoplasia. It was compared against fecal occult blood (FOB) and colonoscopy. Three hundred and seventeen consecutive subjects from 4 different centers were included. Stool specimens were collected before purgation, processed appropriately and were tested for FOB and quantitatively analyzed for M2-PK. Colonoscopies were performed by experienced endoscopists who were unaware of fecal assay results. At cutoff value of 4 U/ml, fecal M2-PK assay had a sensitivity, specificity, PPV and NPV of 81.1, 86.7, 71.1 and 61.9% respectively for diagnosing CRC whereas FOBT showed a sensitivity of 36.5%, specificity of 92.2%, PPV of 72.9% and NPV of 71.5% for CRC. Such low specificity of fecal M2-PK will lead to unacceptably high number of false positives if it is used for mass CRC screening, leading to unindicated colonoscopies with its associated inconveniences, risks and costs. CRC screening test must have high specificity; a high sensitivity is not as vital. To conclude, M2-PK was found to be a poor screening biomarker for CR neoplasia in a subject population at above average risk based on its prospective comparison with colonoscopy. These marginal performance characteristics do not permit its use as a screening tool for CR neoplasia in present clinical settings.