There is tremendous variety of biomarkers, including proteins (e.g., an enzyme or receptor), nucleic acids (e.g., a microRNA or other non-coding RNA), antibodies, and peptides, among other categories. A biomarker can also be a collection of alterations, such as gene expression, proteomic, and metabolomic signatures. Biomarkers can be detected in the circulation (whole blood, serum, or plasma) or excretions or secretions (stool, urine, sputum, or nipple discharge), and thus easily assessed non-invasively and serially, or can be tissue-derived, and require either biopsy or special imaging for evaluation. Genetic biomarkers can be inherited, and detected as sequence variations in germ line DNA isolated from whole blood, sputum, or buccal cells, or can be somatic, and identified as mutations in DNA derived from tumor tissue.

A number of tumor markers are currently being used for a wide range of cancer types. Tumor markers that are currently in common use are listed below.

ALK gene rearrangements and overexpression(Non-small cell lung cancer and anaplastic large cell lymphoma)

Alpha-fetoprotein (AFP) (Liver cancer and germ cell tumors)

Beta-2-microglobulin (B2M)(Multiple myeloma, chronic lymphocytic leukemia, and some lymphomas)

Beta-human chorionic gonadotropin (Beta-hCG) (Choriocarcinoma and germ cell tumors)

BRCA1 and BRCA2 gene mutations (Ovarian cancer)

BCR-ABL fusion gene (Philadelphia chromosome) (Chronic myeloid leukemia, acute lymphoblastic leukemia, and acute myelogenous leukemia)

BRAF V600 mutations (Cutaneous melanoma and colorectal cancer)

C-kit/CD117(Gastrointestinal stromal tumor and mucosal melanoma)

CA15-3/CA27.29(Breast cancer)

CA19-9(Pancreatic cancer, gallbladder cancer, bile duct cancer, and gastric cancer)

CA-125(Ovarian cancer)

Calcitonin(Medullary thyroid cancer)

Carcinoembryonic antigen (CEA)(Colorectal cancer and some other cancers)

CD20(Non-Hodgkin lymphoma)

Chromogranin A (CgA)(Neuroendocrine tumors)

Chromosomes 3, 7, 17, and 9p21(Bladder cancer)

Circulating tumor cells of epithelial origin (CELLSEARCH®)(Metastatic breast, prostate, and colorectal cancers)

Cytokeratin fragment 21-1(Lung cancer)

EGFR gene mutation analysis(Non-small cell lung cancer)

Estrogen receptor (ER)/progesterone receptor (PR)(Breast cancer)

Fibrin/fibrinogen(Bladder cancer)

HE4(Ovarian cancer)

HER2/neu gene amplification or protein overexpression(Breast cancer, gastric cancer, and gastroesophageal junction adenocarcinoma)

Immunoglobulins(Multiple myeloma and Waldenström macroglobulinemia)

KRAS gene mutation analysis(Colorectal cancer and non-small cell lung cancer)

Lactate dehydrogenase(Germ cell tumors, lymphoma, leukemia, melanoma, and neuroblastoma)

Neuron-specific enolase (NSE)(Small cell lung cancer and neuroblastoma)

Nuclear matrix protein 22(Bladder cancer)

Programmed death ligand 1 (PD-L1)(Non-small cell lung cancer)

Prostate-specific antigen (PSA)(Prostate cancer)

Thyroglobulin(Thyroid cancer)

Urokinase plasminogen activator (uPA) and plasminogen activator inhibitor (PAI-1)(Breast cancer)

5-Protein signature (OVA1®)(Ovarian cancer)

21-Gene signature (Oncotype DX®)(Breast cancer)

70-Gene signature (Mammaprint®)(Breast cancer)

Source: National Cancer Institute website: