A tumor marker is a biomarker found in the blood, urine, or body tissues that can be elevated in cancer, among other tissue types. There are many different tumor markers, each indicative of a particular disease process, and they are used in oncology to help detect the presence of cancer. An elevated level of a tumor marker can indicate cancer; however, there can also be other causes of the elevation.
Tumor markers can be produced directly by the tumor or by non-tumor cells as a response to the presence of a tumor. Most tumor markers are tumor antigens, but not all tumor antigens can be used as tumor markers.
Diagnosis of specific tumor types, particularly in certain brain tumors and other instances where biopsy is not feasible.
As stated in the BMJ 2009, tumour markers should not generally be used for the purpose of diagnosis of cancers, as opposed to monitoring purposes in certain cancers, or in certain cases, screening purposes. The use of these tests without understanding their utility has resulted in inappropriate use of tumour marker blood tests, which has also resulted in further inappropriate over-investigation for cancers.
If repeated measurements of tumor marker are needed, some clinical testing laboratories provide a special reporting mechanism, a serial monitor, that links test results and other data pertaining to the person being tested. This requires a unique identifier for the person. In the United States commonly a Social Security number & Civil Personal Record (CPR) in Bahrain are used for this. One important function of this mechanism is to ensure that each test is performed using the same assay kit. For example, for AFP many different commercial assay kits, based on different technologies, are available. AFP measurements obtained using different assay kits are not comparable unless special calculations are performed.
Interlaboratory proficiency testing for tumor marker tests, and for clinical tests more generally, is an emerging field.In the United States, New York state is prominent in advocating such research.
The high dose hook effect is an artefact of tumor marker immunoassay kits, that causes the reported quantity of tumor marker to be incorrectly low when the quantity is high. An undetected hook effect may cause delayed recognition of a tumor. The hook effect can be detected by analyzing serial dilutions. The hook effect is absent if the reported quantities of tumor marker in a serial dilution are proportional to the dilution.
Multiple Tumor marker test
There are 4 things that should be considered about a Tumor marker test:
Sensitivity, no Tumor marker test has 100 percent sensitivity, so some tumors are still not detected by a single Tumor marker test
Specificity, only the M2-PK Tumor marker test for colorectal has up to 95 percent specificity
False Negative, the result is negative, but in fact is positive, so it is very dangerous; until now only the M2-PK Tumor marker test which analyzes the DNA has no false negative
False Positive, the result is positive, but in fact is negative, because the test result is positive, so another test(s) or biopsy should be done
Multiple Tumor marker tests will give a more exact result; these are:
Colorectal: M2-PK, if M2-PK is not available, so can test CEA, CA 19-9, CA 125
Breast: CEA, CA 15-3, Cyfra 21-1
Ovary: CEA, CA 19-9, CA 125, AFP, BHCG
Uterine: CEA, CA 19-9, CA 125, Cyfra 21-1, SCC
Prostate: PSA, FPSA and ratio
Testicle: AFP, BHCG
Pancreas/Stomach: CEA, CA 19-9, CA 72-4
Liver: CEA, AFP
Oesophagus: CEA, Cyfra 21-1
Thyroid: CEA, NSE
Lung: CEA, CA 19-9, CA 125, NSE, Cyfra 21-1 (Sensitivity at 95 percent percentile for Cyfra 21-1 is 79 percent, while for SCC and CEA are 41 and 31 percent respectively)
^Keshaviah, A; Dellapasqua, S; Rotmensz, N; Lindtner, J; Crivellari, D; Collins, J; Colleoni, M; Thurlimann, B et al. (2006). "CA15-3 and alkaline phosphatase as predictors for breast cancer recurrence: A combined analysis of seven International Breast Cancer Study Group trials". Annals of Oncology18 (4): 701–8. doi:10.1093/annonc/mdl492. PMID17237474.
^Osman N, O'Leary N, Mulcahy E, Barrett N, Wallis F, Hickey K, Gupta R (September 2008). "Correlation of serum CA125 with stage, grade and survival of patients with epithelial ovarian cancer at a single centre". Ir Med J101 (8): 245–7. PMID18990955.
^Bast RC, Xu FJ, Yu YH, Barnhill S, Zhang Z, Mills GB (1998). "CA 125: the past and the future". Int. J. Biol. Markers13 (4): 179–87. PMID10228898.
^Bagan P, Berna P, Assouad J, Hupertan V, Le Pimpec Barthes F, Riquet M (January 2008). "Value of cancer antigen 125 for diagnosis of pleural endometriosis in females with recurrent pneumothorax". Eur. Respir. J.31 (1): 140–2. doi:10.1183/09031936.00094206. PMID17804443.
^Haug, U; Rothenbacher, D; Wente, M N; Seiler, C M; Stegmaier, C; Brenner, H (2007). "Tumour M2-PK as a stool marker for colorectal cancer: Comparative analysis in a large sample of unselected older adults vs colorectal cancer patients". British Journal of Cancer. doi:10.1038/sj.bjc.6603712.
^Lüftner, D; Mesterharm, J; Akrivakis, C; Geppert, R; Petrides, PE; Wernecke, KD; Possinger, K (2000). "Tumor type M2 pyruvate kinase expression in advanced breast cancer". Anticancer research20 (6D): 5077–82. PMID11326672.
^Benesch, C; Schneider, C; Voelker, HU; Kapp, M; Caffier, H; Krockenberger, M; Dietl, J; Kammerer, U; Schmidt, M (2010). "The clinicopathological and prognostic relevance of pyruvate kinase M2 and pAkt expression in breast cancer". Anticancer research30 (5): 1689–94. PMID20592362.
^Oremek, GM; Sapoutzis, N; Kramer, W; Bickeböller, R; Jonas, D (2000). "Value of tumor M2 (Tu M2-PK) in patients with renal carcinoma". Anticancer research20 (6D): 5095–8. PMID11326675.
^Wechsel, HW; Petri, E; Bichler, KH; Feil, G (1999). "Marker for renal cell carcinoma (RCC): The dimeric form of pyruvate kinase type M2 (Tu M2-PK)". Anticancer research19 (4A): 2583–90. PMID10470199.
^Schneider, J; Peltri, G; Bitterlich, N; Philipp, M; Velcovsky, HG; Morr, H; Katz, N; Eigenbrodt, E (2003). "Fuzzy logic-based tumor marker profiles improved sensitivity of the detection of progression in small-cell lung cancer patients". Clinical and experimental medicine2 (4): 185–91. doi:10.1007/s102380300005. PMID12624710.
^Oremek, G; Kukshaĭte, R; Sapoutzis, N; Ziolkovski, P (2007). "The significance of TU M2-PK tumor marker for lung cancer diagnostics". Klinicheskaia meditsina85 (7): 56–8. PMID17882813.
^Hardt, PD; Ngoumou, BK; Rupp, J; Schnell-Kretschmer, H; Kloer, HU (2000). "Tumor M2-pyruvate kinase: A promising tumor marker in the diagnosis of gastro-intestinal cancer". Anticancer research20 (6D): 4965–8. PMID11326648.
^ abKumar, Yogesh; Tapuria, Niteen; Kirmani, Naveed; Davidson, Brian R. (2007). "Tumour M2-pyruvate kinase: A gastrointestinal cancer marker". European Journal of Gastroenterology & Hepatology19 (3): 265. doi:10.1097/MEG.0b013e3280102f78.
^Kaura, B; Bagga, R; Patel, FD (2004). "Evaluation of the Pyruvate Kinase isoenzyme tumor (Tu M2-PK) as a tumor marker for cervical carcinoma". The journal of obstetrics and gynaecology research30 (3): 193–6. doi:10.1111/j.1447-0756.2004.00187.x. PMID15210041.
^Ahmed, AS; Dew, T; Lawton, FG; Papadopoulos, AJ; Devaja, O; Raju, KS; Sherwood, RA (2007). "M2-PK as a novel marker in ovarian cancer. A prospective cohort study". European journal of gynaecological oncology28 (2): 83–8. PMID17479666.
^Leboeuf, R.; Langlois, Marie-France; Martin, Marc; Ahnadi, Charaf E.; Fink, Guy D. (2005). ""Hook Effect" in Calcitonin Immunoradiometric Assay in Patients with Metastatic Medullary Thyroid Carcinoma: Case Report and Review of the Literature". Journal of Clinical Endocrinology & Metabolism91 (2): 361. doi:10.1210/jc.2005-1429.