CEACAM5 has different expression patterns in gastric non-neoplastic and neoplastic lesions and cytoplasmic staining is a marker for evaluation of tumor progression in gastric adenocarcinoma.

Objective: The aim of this study was to investigate the expression patterns of CEACAM5 in non-neoplastic and neoplastic gastric lesions, as well as its application in the differential diagnosis and its relationship with tumor progression.

Methods: CEACAM5 expression was detected by immunohistochemical staining in the serial sections of the gastric neoplastic and non-neoplastic lesions. The impacts of CEACAM5 expression patterns on tumor progression were evaluated by statistics, the clinical and pathological data included sex, age, tumor extension, lymph node involvement and tumor staging.

Results: There was no CEACAM5 expression in normal gastric epithelial cells. In hyperplastic polyps, CEACAM5 was expressed with apical membranous staining in the hyperplastic and prolonged gastric pit adjacent to the surface. Intestinal metaplasia (IM) expressed CEACAM5 mainly with membranous pattern, and some cases showed membranous staining mixed with cytoplasmic staining. GIN expressed CEACAM5 mainly with membranous staining, but the mixed staining of cytoplasmic and membranous patterns increased, and especially in the high grade GIN, cytoplasmic staining of CEACAM5 began to occur. Compared with IM and GIN, CEACAM5 expression patterns of hyperplastic polyp showed a significant difference (P=0.000). IM, low grade GIN and the whole GIN showed no significant difference in CEACAM5 expression patterns (P=0.355), but IM and high grade GIN showed a significant difference (P=0.027). There was a significant difference between low and high grade GIN (P=0.002). GIN and well-differentiated carcinomas showed no significant difference (P=0.070), but low grade GIN and well differentiated carcinomas showed a significant difference (P=0.006). In gastric adenocarcinomas, CEACAM5 expression patterns showed a significant difference in tumor grading (P=0.010) and Laurén classification (P=0.001). In histological grading, well differentiated carcinomas showed more membranous staining than moderately and poorly differentiated, and more cytoplasmic CEACAM5 staining was detected in moderately and poorly differentiated carcinomas. Similar to that, in Laurén classification, intestinal carcinomas showed more membranous staining, and diffuse carcinomas showed more cytoplasmic staining. Moreover, CEACAM5 expression patterns showed a significant difference in tumor extension (P=0.012), lymph node involvement (P=0.015) and tumor staging (P=0.002), suggesting that CEACAM5 should be involved in tumor progression. In advanced carcinomas, CEACAM5 was expressed with more cytoplasmic staining regardless of the histological classification.

Conclusion: CEACAM5 had different expression patterns in gastric non-neoplastic and neoplastic lesions. The CEACAM5 expression patterns were associated with tumor progression. Membranous staining of CEACAM5 might be a marker of premalignancy in gastric lesions, and cytoplasmic CEACAM5 might enhance tumor invasion and migration and be an evaluated marker for progressive and advanced gastric cancer. Also, it might be useful for the differential diagnosis of gastric premalignant lesions.