Minimum biopsy set for HER2 evaluation in gastric and gastro-esophageal junction cancer

Background and study aims: The HER2 status of small endoscopic biopsies is important for predicting the eligibility of patients with metastatic HER2-positive gastric cancer or gastro-esophageal junction (GEJ) cancer for anti-HER2 therapy approved by the U.S. Food and Drug Administration. The aim of this study was to identify the minimum biopsy set required to evaluate the HER2 status with confidence.

Patients and methods: A total of 103 consecutive patients with resected gastric cancer or GEJ cancer were retrospectively selected; 2 formalin-fixed, paraffin-embedded samples of each surgical specimen and all paired endoscopic biopsies were analyzed for HER2 status with both immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) methods. A total of 10 virtual biopsies were constructed by selecting areas 2.6 mm in diameter on the luminal side of digitalized slides obtained from the surgical specimens. The results of evaluating HER2 status in virtual biopsies, slides containing complete surgical specimens, and endoscopic biopsies were compared. The resulting minimum biopsy set was applied to the endoscopic biopsy series for validation.

Results: A biopsy set containing a minimum of 5 samples was identified as the most accurate in predicting HER2 status (sensitivity, 92 %; specificity, 97 %). In only 3 of the 103 cases (2.9 %) did a comparison of the HER2 evaluation of virtual biopsies and that of entire slides show inconsistent results. Overall agreement between the endoscopic biopsies and surgical samples for HER2 IHC status increased from 78.4 % to 92.3 % when biopsy sets containing 4 or fewer samples were compared with biopsy sets containing 5 or more samples.

Conclusions: Although the recommendations suggest that 8 to 10 biopsies are necessary, the results show that a minimum set of 5 biopsies may be sufficient for reliable HER2 assessment in gastric cancer and GEJ cancer. However, endoscopists should be aware that a smaller sample size may be less accurate in selecting patients eligible for anti-HER2 therapy.

^* These autors contributed equally.

• References

• 1 International Agency for Research on Cancer. Globocan: estimated cancer incidence, mortality and prevalence worldwide in 2012. 2012 Available from: http://globocan.iarc.fr Accessed December 13, 2014
• 2 Crew KD, Neugut AI. Epidemiology of gastric cancer. World J Gastroenterol 2006; 12: 354-362
• 3 Lepage C, Drouillard A, Jouve JL et al. Epidemiology and risk factors for oesophageal adenocarcinoma. Dig Liver Dis 2013; 45: 625-629
• 4 Hudis CA. Trastuzumab—mechanism of action and use in clinical practice. N Engl J Med 2007; 357: 39-51
• 5 Yano T, Doi T, Ohtsu A et al. Comparison of HER2 gene amplification assessed by fluorescence in situ hybridization and HER2 protein expression assessed by immunohistochemistry in gastric cancer. Oncol Rep 2006; 15: 65-71
• 6 Kim MA, Lee HJ, Yang HK et al. Heterogeneous amplification of ERBB2 in primary lesions is responsible for the discordant ERBB2 status of primary and metastatic lesions in gastric carcinoma. Histopathology 2011; 59: 822-831
• 7 Marx AH, Tharun L, Muth J et al. HER-2 amplification is highly homogenous in gastric cancer. Hum Pathol 2009; 40: 769-777
• 8 Fassan M, Mastracci L, Grillo F et al. Early HER2 dysregulation in gastric and oesophageal carcinogenesis. Histopathology 2012; 61: 769-776
• 9 Fassan M, Pizzi M, Realdon S et al. The HER2-miR125a5p/miR125b loop in gastric and esophageal carcinogenesis. Hum Pathol 2013; 44: 1804-1810
• 10 Jørgensen JT, Hersom M. HER2 as a prognostic marker in gastric cancer – a systematic analysis of data from the literature. J Cancer 2012; 3: 137-144
• 11 Bang YJ, Van Cutsem E, Feyereislova A et al. Trastuzumab in combination with chemotherapy versus chemotherapy alone for treatment of HER2-positive advanced gastric or gastro-oesophageal junction cancer (ToGA): a phase 3, open-label, randomised controlled trial. Lancet 2010; 376: 687-697
• 12 European Medicine Agency, Committee for Medicinal Products for Human Use. Post-authorisation summary of positive opinion for Herceptin: international nonproprietary name (INN): trastuzumab. Available from: http://www.ema.europa.eu/docs/en_GB/document_library/Summary_of_opinion/human/000278/WC500059913.pdf Accessed December 14, 2014
• 13 U.S. Food and Drug Administration. Trastuzumab. Available from: http://www.fda.gov/AboutFDA/CentersOffices/OfficeofMedicalProductsandTobacco/CDER/ucm230418.htm Accessed December 14, 2014
• 14 Hofmann M, Stoss O, Shi D et al. Assessment of a HER2 scoring system for gastric cancer: results from a validation study. Histopathology 2008; 52: 797-805
• 15 Grabsch H, Sivakumar S, Gray S et al. HER2 expression in gastric cancer: rare, heterogeneous and of no prognostic value—conclusions from 924 cases of two independent series. Cell Oncol 2010; 32: 57-65
• 16 Grillo F, Fassan M, Ceccaroli C et al. The reliability of endoscopic biopsies in assessing HER2 status in gastric and gastroesophageal junction cancer: a study comparing biopsies with surgical samples. Transl Oncol 2013; 6: 10-16
• 17 Yang J, Luo H, Li Y et al. Intratumoral heterogeneity determines discordant results of diagnostic tests for human epidermal growth factor receptor (HER) 2 in gastric cancer specimens. Cell Biochem Biophys 2012; 62: 221-228
• 18 Lee KE, Lee HJ, Kim YH et al. Prognostic significance of p53, nm23, PCNA and c-erbB-2 in gastric cancer. Jpn J Clin Oncol 2003; 33: 173-179
• 19 Fusco N, Rocco EG, Del Conte C et al. HER2 in gastric cancer: a digital image analysis in pre- neoplastic, primary and metastatic lesions. Mod Pathol 2013; 26: 816-824
• 20 Rüschoff J, Dietel M, Baretton G et al. HER2 diagnostics in gastric cancer-guideline validation and development of standardized immunohistochemical testing. Virchows Arch 2010; 457: 299-307
• 21 Rüschoff J, Hanna W, Bilous M et al. HER2 testing in gastric cancer: a practical approach. Mod Pathol 2012; 25: 637-650
• 22 Hechtman JF, Polydorides AD. HER2/neu gene amplification and protein overexpression in gastric and gastroesophageal junction adenocarcinoma: a review of histopathology, diagnostic testing, and clinical implications. Arch Pathol Lab Med 2012; 136: 691-697
• 23 Mastracci L, Bruno S, Spaggiari P et al. The impact of biopsy number and site on the accuracy of intestinal metaplasia detection in the stomach. A morphometric study based on virtual biopsies. Dig Liver Dis 2008; 40: 632-640
• 24 Park YS, Hwang HS, Park HJ et al. Comprehensive analysis of HER2 expression and gene amplification in gastric cancers using immunohistochemistry and in situ hybridization: which scoring system should we use?. Hum Pathol 2012; 43: 413-422
• 25 Ajani JA, Barthel JS, Bekaii-Saab T et al. Gastric cancer. J Natl Compr Canc Netw 2010; 8: 378-409
• 26 Moehler M, Al-Batran SE, Andus T et al. German S3-guideline: diagnosis and treatment of esophagogastric cancer. Z Gastroenterol 2011; 49: 461-531
• 27 Warneke VS, Behrens HM, Böger C et al. Her2/neu testing in gastric cancer: evaluating the risk of sampling errors. Ann Oncol 2013; 24: 725-733