Where should gastric biopsies be performed when areas of intestinal metaplasia are observed?

Abstract

with a poor 5-year survival rate, partly due to its late diagnosis. Early detection can significantly increase survival and, therefore, identification of patients with higher GC risk (e. g. premalignant conditions) who may benefit from surveillance is essential for decreasing its mortality [1]. Intestinal-type adenocarcinoma, the most frequent histological type, is preceded by a cascade of precancerous lesions such as atrophic gastritis and gastric intestinal metaplasia (IM). Thus, in the absence of screening strategies in European countries, the MAPS II Guideline recommends opportunistic identification and follow-up of individuals at high risk [1], namely those with advanced stages of atrophic gastritis. Because the correlation between white light endoscopy (WLE) and histological findings is poor and use of chromoendoscopy is cumbersome, two classifications of advanced atrophic changes based on random biopsies have been proposed: Operative Link for Gastritis Assessment (OLGA) and Operative Link on Gastritis/Intestinal Metaplasia (OLGIM). Some reports have shown that IM is the most reliable marker for this purpose due to its higher interobserver agreement, besides the lack of validated endoscopic pattern of atrophic gastritis. Hence, OLGIM to OLGA is preferable, under European Society of Gastrointestinal Endoscopy Guideline MAPS II, for staging gastritis [1]. However, to improve endoscopic diagnostic accuracy, different real-time techniques using imaging-enhanced endoscopy (IEE) emerged. The major advantages are that they are easy to employ and allow precise observation of the entire gastric mucosa and microvascular pattern. Prior reports evaluated the diagnostic efficacy of these technologies, most of them focusing on narrow-band imaging (NBI). A systematic review showed a pooled sensitivity and specificity of NBI of 0.87 and 0.77, respectively, for IM diagnosis, and 0.90 and 0.83 for dysplasia/cancer diagnosis [2]. More recently, our group reported excellent results in diagnostic yield of NBI in addition to high resolution-WLE (HR-WLE), achieving a global accuracy superior to 90% in detection of IM and dysplasia [3]. In fact, the concept of random biopsies is now arguable with widespread use of virtual chromoendoscopy (CE) which, at the touch of a button, has been shown to significantly improve endoscopic-histological concordance. Due to the multifocal and patchy distribution presented in most cases of IM, biopsy samples (which represent only a very small part of the entire mucosa) are prone to sampling error, and for these reasons, it seems more logical to rely on endoscopic assessment of the entire mucosa to stratify GC risk instead of depending on random biopsies. But are CE-targeted-biopsies better than SydneyHouston random biopsies for mapping? Results from some reports suggest that targeted biopsies are not inferior, but random biopsies may detect some cases of IM that are not identified with only NBI [4]. However, this difference does not appear to have a significant clinical meaning because most NBI missed areas will be mild and focal IM, so without necessity of surveillance in most cases. In fact, Buxbaum et al analyzed the diagnostic yield of mapping (biopsies according to the updated Sidney protocol) + WLE vs. NBI + WLE vs. NBI + mapping and the best results were with NBI + mapping (100% detection of patients with IM and 94.7% of gastric locations of IM [4]). Consequently, considering the diagnostic yield of random biopsies and the possibility of missing important changes in Where should gastric biopsies be performed when areas of intestinal metaplasia are observed?