The Diagnostic Value Of "Increased Whitening" And "Delayed Disappearance" For Gastric Intestinal Metaplasia In Acetic Acid Chromoendoscopy

BackgroundGastric cancer is one of the most common malignancies and the second leading cause of death from cancer worldwide.Both pathological and epidemiological studies prove that the stomach tumorigenesis is a multi-step process.Gastric intestinal metaplasia(GIM),the well-known precancerous condition for intestinal-type gastric cancer,has been paid much more attention now.Early detection and treatment of GIM can significantly inhibit the progression of gastric cancer.Current diagnosis of GIM,which usually appears in flat mucosa and shows few morphologic changes,still relies on the histology of biopsy specimens.However,conventional endoscopic identification of GIM has an unsatisfactory intraobserver agreement and a poor correlation with histopathologic findings.Acetic acid chromoendoscopy(AAC)is one of the novel techniques for a better visual recognition of GIM.After the application of acetic acid,the surface patterns are more easily recognizable,which corresponds to the swelling effect of acetic acid.Tanaka et al.classified the enhanced surface patterns into five types:type ?,small round pits of uniformsize and shape;type ?,slit-like pits;type ?,gyrus and villous patterns;type IV,irregular arrangement and size;and type ?,destructive pattern.The type ?,gyrus and villous patterns,was considered to have a high correlation with the presence of GIM.However,for the observations of fine surface patterns,magnifying endoscopes should be used,which are complex to perform and also unavailable for most units of primary hospitals.All these have hampered the widespread acceptance of this technique.The acetowhitening reaction is a further important aspect of AAC.Previous studies have shown its bright prospects for recognizing gastrointestinal(GI)neoplastic lesions.Yagi et al.reported that the gastric cancerous lesions lost their white appearance much sooner than noncancerous areas and concluded it was useful for the diagnosis of gastric neoplasia.This difference was also confirmed by Longcroft-Wheaton et al.in Barrett's esophagus.They reported that the duration of acetowhitening of less than 142 seconds could identify neoplastic areas in Barrett's esophagus with a sensitivity of 97%and a specificity of 84%.However,research on the application of acetowhitening reaction for identifying GIM remains lacking to date.Aims1.We aimed to explore the role of acetowhitening reaction in optical diagnosis of GIM.2.We also aimed to compare the accuracy of acetowhitneing with white-light endoscopy(WLE)in performing the optical diagnosis of GIM.Methods1.Pilot studyIn order to explore the feature of acetowhitening reaction of GIM,patients with known GIM were enrolled for a pilot study,in which AAC was performed for each included patient.2.Validation studyBetween June 2016 and August 2016 consecutive patients with GIM or suspected GIM presenting to the endoscopy unit of Qilu Hospital(Jinan,Shandong,China)were recruited into the prospective study.First,WLE was performed for each included patient.After that,1.5%acetic acid was sprinkled evenly onto the antrum,angle and corpus of the stomach,diagnoses of lesions were made just based on the features of acetowhitening reaction.Finally,biopsy sampling was undertaken for all areas included for evaluation.For the patient in whom no suspicious area could be detected by either WLE or AAC,biopsies were taken from the five standard sites following the updated Sydney System.The histopathological diagnoses were made by an experienced GI pathologist.Moreover,we evaluated interobserver and intraobserver agreements for the diagnoses of GIM by using this new method.Results1.Pilot studyThe acetowhitening reaction in GIM areas always showed an increased whitening and a longer duration compared with that in the adjacent normal mucosa,which we termed as "increased whiteness(IW)" and "delayed disappearance(DD)" respectively.We defined these two indicators as the particular features of GIM after spraying of acetic acid.2.Validation studyA total of 190 sites from 82 patients(48 men,34 women,mean age 52.87 years)were included.Among these sites,92 were proved to be GIM histopathologically.The sensitivity,specificity and accuracy of WLE for diagnosing GIM were 38.04%,95.92%and 67.89%,respectively.The sensitivity,specificity and accuracy of AAC for diagnosing GIM were 90.22%,90.82%and 90.53%,respectively.The diagnostic sensitivity of AAC was significantly higher than that of WLE(p<0.001).The diagnostic specificities of AAC and WLE did not differ significantly(p = 0.229).The interobserver and intraobserver agreements were both excellent for the identifications of IW(mean k,0.88 and 0.92,respectively)and DD(mean k,0.83 and 0.88,respectively).ConclusionsThe AAC based on IW and DD is a simple but effective method for the optical diagnosis of GIM.