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|It has been suggested that this article be merged with Cancer biomarkers. (Discuss) Proposed since May 2014.|
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.
Although mammography, ultrasonography, computed tomography, magnetic resonance imaging scans, and tumor marker assays help in the staging and treatment of the cancer, they are usually not definitive diagnostic tests. The diagnosis is confirmed by biopsy.
Uses of tumor markers can broadly be classified as follows:
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.
Tumor markers can be detected by immunohistochemistry.
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.
|Tumor marker||Associated tumor types|
|Alpha fetoprotein (AFP)||germ cell tumor, hepatocellular carcinoma|
|CA19-9||Mainly pancreatic cancer, but also colorectal cancer and other types of gastrointestinal cancer.|
|CA-125||Mainly ovarian cancer, but may also be elevated in for example endometrial cancer, fallopian tube cancer, lung cancer, breast cancer and gastrointestinal cancer. May also increase in endometriosis.|
|Calcitonin||medullary thyroid carcinoma|
|Calretinin||mesothelioma, sex cord-gonadal stromal tumour, adrenocortical carcinoma, synovial sarcoma|
|Carcinoembryonic antigen||gastrointestinal cancer, cervix cancer, lung cancer, ovarian cancer, breast cancer, urinary tract cancer|
|CD34||hemangiopericytoma/solitary fibrous tumor, pleomorphic lipoma, gastrointestinal stromal tumor, dermatofibrosarcoma protuberans|
|CD99||Ewing sarcoma, primitive neuroectodermal tumor, hemangiopericytoma/solitary fibrous tumor, synovial sarcoma, lymphoma, leukemia, sex cord-gonadal stromal tumour|
|CD117||gastrointestinal stromal tumor, mastocytosis, seminoma|
|Chromosomes 3, 7, 17, and 9p21||bladder cancer|
|Cytokeratin (various types)||Many types of carcinoma, some types of sarcoma|
|Desmin||smooth muscle sarcoma, skeletal muscle sarcoma, endometrial stromal sarcoma|
|Epithelial membrane protein (EMA)||many types of carcinoma, meningioma, some types of sarcoma|
|Factor VIII, CD31 FL1||vascular sarcoma|
|Glial fibrillary acidic protein (GFAP)||glioma (astrocytoma, ependymoma)|
|Gross cystic disease fluid protein (GCDFP-15)||breast cancer, ovarian cancer, salivary gland cancer|
|HMB-45||melanoma, PEComa (for example angiomyolipoma), clear cell carcinoma, adrenocortical carcinoma|
|Human chorionic gonadotropin (hCG)||gestational trophoblastic disease, germ cell tumor, choriocarcinoma|
|inhibin||sex cord-gonadal stromal tumour, adrenocortical carcinoma, hemangioblastoma|
|keratin (various types)||carcinoma, some types of sarcoma|
|lymphocyte marker (various types||lymphoma, leukemia|
|MART-1 (Melan-A)||melanoma, steroid-producing tumors (adrenocortical carcinoma, gonadal tumor)|
|Myo D1||rhabdomyosarcoma, small, round, blue cell tumour|
|muscle-specific actin (MSA)||myosarcoma (leiomyosarcoma, rhabdomyosarcoma)|
|neurofilament||neuroendocrine tumor, small-cell carcinoma of the lung|
|neuron-specific enolase (NSE)||neuroendocrine tumor, small-cell carcinoma of the lung, breast cancer|
|placental alkaline phosphatase (PLAP)||seminoma, dysgerminoma, embryonal carcinoma|
|PTPRC (CD45)||lymphoma, leukemia, histiocytic tumor|
|S100 protein||melanoma, sarcoma (neurosarcoma, lipoma, chondrosarcoma), astrocytoma, gastrointestinal stromal tumor, salivary gland cancer, some types of adenocarcinoma, histiocytic tumor (dendritic cell, macrophage)|
|smooth muscle actin (SMA)||gastrointestinal stromal tumor, leiomyosarcoma, PEComa|
|thyroglobulin||post-operative marker of thyroid cancer (but not in medullary thyroid cancer)|
|thyroid transcription factor-1||all types of thyroid cancer, lung cancer|
|Tumor M2-PK||colorectal cancer, Breast cancer, renal cell carcinoma Lung cancer, Pancreatic cancer, Esophageal Cancer, Stomach Cancer,Cervical Cancer, Ovarian Cancer,|
|vimentin||sarcoma, renal cell carcinoma, endometrial cancer, lung carcinoma, lymphoma, leukemia, melanoma|
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.
There are 4 things that should be considered about a Tumor marker test:
Multiple Tumor marker tests will give a more exact result; these are: