Ring studies, where samples are assessed and compared by several laboratories in a sequential manner, can provide valuable information on interlaboratory IHC and ISH consensus and on factors that may lead to discordant results; in breast cancer, ring studies have been proven to be a successful tool for standardizing HER2 testing and scoring, and a similar approach may be effective in gastric cancer [27]. Here, ERBB2 is linked to breast carcinoma.