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A test that uses glowing DNA probes on a tissue slide to count gene copies or spot rearranged genes inside individual cells, used to confirm HER2 amplification, MYCN in neuroblastoma, or ALK and MYC rearrangements.
Fluorescence in situ hybridisation (or chromogenic ISH) shows whether a gene is amplified (extra signals per nucleus, as in HER2 with ratio ≥2.0 or ≥6 copies), deleted (del(17p) in CLL, 1p/19q in oligodendroglioma) or broken and rejoined (break-apart probes for ALK, ROS1, MYC, BCL2, BCL6 in 'double-hit' lymphoma). It works on routine fixed tissue and resolves equivocal IHC 2+ HER2 results. Interphase FISH is standard in myeloma and leukaemia cytogenetics; EBER ISH detects Epstein-Barr virus in tumours. NGS increasingly replaces it for fusions.
Showing the technology this term belongs to: Histopathology & immunohistochemistry.
The glossary entry explains the word; the readout page carries the scoring rule, the thresholds approvals use, the companion diagnostics and the tests.
A direct check of the HERIZON-BTC-01 testing algorithm in routine pathology: IHC 3+ can stand alone, 2+ needs ISH, and the low-level amplification in weakly stained tumours is the group where HER2 drugs are least likely to help.
The highest gallbladder HER2 rate in the literature comes from whole resected tumours scored generously; biopsy-based trial screening finds fewer. Heterogeneity is the practical warning for pathologists and for why HER2-directed drugs do not work in every positive tumour.
It is the document that defines what a complete lung cancer molecular report looks like, and its asymmetry about plasma, rule in but never rule out, is the single most useful sentence in it.
The prevalence estimate that made HER2 the first gallbladder-relevant target; it argues for testing every advanced gallbladder cancer, since one in five may qualify for zanidatamab or trastuzumab deruxtecan.
It fixes the population size for HER2-directed therapy, shows the enrichment in wild-type disease that makes reflex HER2 testing worthwhile there, and establishes that HER2 is not itself prognostic in this cancer.
It is the threshold behind the colorectal HER2 approvals: the more-than-50% rule, rather than the 10% used in gastric cancer, is what a pathologist applies when a bowel cancer is called HER2-positive.
It defined a class of lung cancer by a rearrangement and a clinical phenotype at the same time, and it is the reason ROS1 testing is recommended for every patient with adenocarcinoma rather than only for those with an obvious risk profile.
It was the first evidence that neuroendocrine prostate cancer is a distinct molecular disease with its own candidate drug target, and it started the programme of Aurora kinase trials in this setting, which have since disappointed.
Shares UroVysion Bladder Cancer Kit, Frequent and focal FGFR1 amplification associates with therapeutically tractable FGFR1 dependency in squamous cell lung cancer, ROS1 rearrangements define a unique molecular class of lung cancers, Molecular characterisation of neuroendocrine prostate cancer and identification of new drug targets.
Shares Details of human epidermal growth factor receptor 2 status in 454 cases of biliary tract cancer, HER2 overexpression and amplification as a potential therapeutic target in colorectal cancer: analysis of 3256 patients enrolled in the QUASAR, FOCUS and PICCOLO colorectal cancer trials, HER2 status in extrahepatic cholangiocarcinoma and gallbladder carcinoma: concordance between immunohistochemistry and chromogenic in situ hybridization in 140 cases, Assessment of a HER2 scoring system for colorectal cancer: results from a validation study.
Shares Details of human epidermal growth factor receptor 2 status in 454 cases of biliary tract cancer, SS18::SSX fusion (synovial sarcoma), HER2/HER3 pathway in biliary tract malignancies; systematic review and meta-analysis: a potential therapeutic target?, HER2 testing in the UK: reflex ISH, the ratio against the copy number, and where the UK differs from ASCO/CAP.
Shares Ependymoma molecular groups (PF-A, PF-B, ZFTA, YAP1, MYCN), MYCN amplification, Segmental chromosomal aberrations and ploidy (neuroblastoma), MYCN (N-myc).
Shares TMPRSS2-ERG fusion (and the other ETS rearrangements), Recurrent fusion of TMPRSS2 and ETS transcription factor genes in prostate cancer, Lung cancer (all types), Breast cancer (all types).
Shares HER2 testing in the UK: reflex ISH, the ratio against the copy number, and where the UK differs from ASCO/CAP, HER2 IHC 2+ (equivocal, reflex to ISH), HER2-low (IHC 1+ or IHC 2+/ISH-negative), HER2-positive (IHC 3+ or ISH-amplified).
Shares Reflex HER2 testing of every advanced gallbladder and extrahepatic biliary cancer, HER2 IHC 2+ (equivocal, reflex to ISH), HER2 testing in biliary tract cancer (IHC, ISH and NGS), HER2 ISH amplified (ERBB2 gene amplification).
Shares ROS1 rearrangements define a unique molecular class of lung cancers, TMPRSS2-ERG fusion (and the other ETS rearrangements), Anaplastic lymphoma kinase inhibition in non-small-cell lung cancer, Identification of the transforming EML4-ALK fusion gene in non-small-cell lung cancer.