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ERBB2-associated gastric carcinoma

Monday 13 February 2012

HER2-associated gastric carcinoma; HER2-driven gastric carcinoma

Assessement of the HER2 status

- immunohistochemistry (IHC)
- in situ hybridization (ISH)
- bright-field ISH [chromogenic (CISH) or silver (SISH)] using both HER2 copy number and HER2:chr17 (chromosome 17) ratio.
- fluorescence ISH (FISH)

An IHC3+ score was strongly predictive of a positive ISH result, although agreement for all IHC scores was only moderate, suggesting that IHC triage before ISH testing would be the most cost-effective strategy.

However, because of the unique features of GC/GJC samples and the difficulty of ensuring consistent HER2 staining in the community setting, it is recommended that HER2 status in advanced GC/GJC be determined by both IHC and ISH in the same laboratory.

Management

Trastuzumab provides a survival benefit in patients with human epidermal growth factor receptor 2 (HER2)-amplified/overexpressed advanced gastric and gastroesophageal junction cancers (GC/GJCs).

References

- Gastric HER2 Testing Study (GaTHER): An Evaluation of Gastric/Gastroesophageal Junction Cancer Testing Accuracy in Australia.
B Fox S, Kumarasinghe MP, Armes JE, Bilous M, Cummings MC, Farshid G, Fitzpatrick N, Francis GD, McCloud PI, Raymond W, Morey A. Am J Surg Pathol. 2012 Feb 3. PMID: 22314190