HER2 protein testing in gastric cancer: a retrospective analysis of 1 471 cases during two different periods in a single medical center / 中华病理学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To study the potential factors in influencing the performance of immunohistochemical testing for HER2 protein in gastric cancers.</p><p><b>METHODS</b>The HER2 protein expression status of 1 471 surgically resected archival gastric cancer cases in Drum Tower Hospital collected during two different periods was retrospectively analyzed. The materials included 957 cases tested during the period from 2007 to 2009 (group 1) and 514 cases from 2012 to 2013 (group 2). The test procedures and results observed during these two periods were compared.</p><p><b>RESULTS</b>The percentages of score 3 HER2 protein expression (14.4%, 74/514 versus 9.5%, 91/957) and score 2 or score 3 HER2 protein expression (27.2%, 140/514 versus 21.7%, 208/957) were both higher in group 2 than in group 1 (P < 0.05). In group 1, the cancer tissue was fixed in 10% formalin, stained manually with HER2 antibody A0485 (Dako) and assessed by different pathologists.In group 2, the tissue was fixed in 10% neutral buffered formalin (pH 7.2), stained using automated immunostaining system (Roche Benchmark XT) with HER2 antibody 4B5 (Ventana) and assessed by a specialized team of pathologists.</p><p><b>CONCLUSION</b>The results of HER2 immunostaining in gastric cancer are influenced by a number of factors including type of fixative, clone number of primary antibody, staining methods and experience of pathologists.</p>