ccount when devising the optimal HER2 testing protocol for gastric cancer and the protocols have been further developed, standardized, and refined in testing and, posttrastuzumab Diosmetin for GAstric cancer, further recommendations have been proposed to ensure quality HER2 testing Rolipram clinical trial based on testing data and expert opinion.1,7,29 Data from the trastuzumab for GAstric cancer study demonstrated that patients with tumors that had high levels of HER2 protein expression derived the greatest benefit from treatment with trastuzumab1 and consequently immunohistochemistry should be the initial testing method, fluorescence in situ hybridization or silver in situ hybridization should be used to retest immunohistochemistry 2þ samples. It is our recommendation that, wherever possible, bright field methodologies are preferred to help to identify regions of heterogeneous staining.
In order to ensure accurate and reproducible HER2 testing results, it is essential that interpretation of sodium butyrate structure HER2 results is performed with strict adherence to the scoring criteria specific for gastric cancer as reported in the trastuzumab for GAstric cancer study and the recommendations of the expert panel, scoring criteria have been developed and published.1 Applying the breast cancer testing principles and scoring criteria to HER2 scoring in patients with gastric cancer may result in the underscoring of tumors, and recent evidence suggests that the rate of false negatives observed may be as high as 50% compared with the trastuzumab for GAstric cancer trial, thus preventing eligible patients having access to trastuzumab therapy.
29 See Table 2 for a comparison of breast andgastric cancer scoring according to the American Society of Clinical Oncology/College of American Pathologists30 and the European Medicines Agency27 recommendations.The following sections Imatinib solubility will provide the most upto date practical guidance on how to conduct HER2 testing in gastric cancer, from initial sample collection through to scoring the results, and how to ensure quality testing through quality assurance schemes. Sample Collection Although the American Society of Clinical Oncology/ College of American Pathologists recommendations for breast cancer30 form a solid basis for HER2 testing in gastric cancer, modifications are required to take into account the unique characteristics of this tumor type.
Both surgical specimens and biopsy samples are acceptable for HER2 testing in gastric prequel cancer and the availability of specimen type may vary according to region: for example, surgical specimens are more common in Japan. On the basis of more standardized fixation conditions, it is generally agreed thatbiopsies are preferred to ensure optimal testing results. A representative block of the cancer, including the intestinal tumor part, should be taken from surgical specimens and when biopsies are taken, adequate numbers of viable endoscopic biopsies of the cancer are recommended for HER2 testing to reflect possible heterogeneity of the tumor.31,32 In countries where it is common for only one or two biopsies to be collected, all available samples should be tested for HER2 status. Tissue microarrays are not suitable for HER2 testing to inform clinical decision making due to the heterogeneous nature of HER2 overexpression.