ERBB2 amplification

Assessment

 FISH
 MPLA
 CGHa (aCGH)

Pathology

 In advanced gastric cancer, HER2 overexpression correlated with nodal stage, and a lymph node ratio greater than 0.5 was more common in HER2-amplified tumors than HER2-nonamplified tumors (69.2% vs. 43.3%, respectively; P=0.086). (#21532492#)

• These findings suggest that further investigations of adjuvant therapy with HER2-targeted therapy for advanced GC are warranted.

Australia experience

In August 2006, the Australian government announced a decision to subsidize trastuzumab therapy for early breast cancer, to commence 6 weeks later. (#21052003#)

It was mandated that HER2 gene amplification, determined by in situ hybridization (ISH), be shown, and that the sponsor company, Roche Products Pty Ltd, should fund this testing.

This announcement potentially required provision of ISH testing for HER2 for every newly diagnosed breast cancer, where previously HER2 testing had been performed by immunohistochemistry with support from a single fluorescence ISH (FISH) reference laboratory for indeterminate cases.

The Australian HER2 Testing Advisory Board, an independent expert group, responded to the challenge of rapidly providing accurate nationwide ISH testing.

Bright-field ISH was selected as the testing platform and a decentralized testing model, with support from a central FISH laboratory, was adopted.

An implementation plan was developed addressing standards for training, accreditation, and quality assurance.

Within 6 weeks, 8 pathology laboratories were accredited for ISH testing and by September 2008, 2 years after the announcement, 22 ISH testing laboratories were taking part in the national program and almost 20,000 ISH tests had been performed.

This article describes the design and rapid implementation of a nationwide program of bright-field ISH as the first-line testing platform for HER2 status in early breast cancer.

This model for the coordinated and large-scale implementation of a new biomarker test has wide application, given that accurate assessment of a range of novel biomarkers is being used increasingly to determine eligibility for new targeted treatment modalities. (#21052003#)

References

 Establishment of the Australian in situ hybridization program for the assessment of HER2 amplification in breast cancer: a model for the introduction of new biomarkers into clinical practice. Farshid G, Armes JE, Bell R, Cummings M, Fox S, Francis G, Haswell M, Morey A, McCue G, Raymond W, Robbins P, Bilous M. Diagn Mol Pathol. 2010 Dec;19(4):187-93. PMID: #21052003#

 Clinicopathologic characteristics of patients with stage III/IV (M(0)) advanced gastric cancer, according to HER2 status assessed by immunohistochemistry and fluorescence in situ hybridization. Im SA, Kim JW, Kim JS, Kim MA, Jordan B, Pickl M, Han SW, Oh DY, Lee HJ, Kim TY, Kim WH, Yang HK, Bang YJ. Diagn Mol Pathol. 2011 Jun;20(2):94-100. PMID: #21532492#

 Validation of the multiplex ligation-dependent probe amplification (MLPA) technique for the determination of HER2 gene amplification in breast cancer. Farshid G, Cheetham G, Davies R, Moore S, Rudzki Z. Diagn Mol Pathol. 2011 Mar;20(1):11-7. PMID: #21326034#

 HER-2 amplification is highly homogenous in gastric cancer. Bilous M, Osamura RY, Rüschoff J, van de Vijver M, Hanna W, Penault-Llorca F, Roche P. Hum Pathol. 2009 Nov 13. PMID: #19914678#