CD44 variant 9 expression in primary early gastric cancer as a predictive marker for recurrence

Abstract

Background: Multiple early gastric cancers (EGCs) may develop in 6-14% of patients even after achieving curative endoscopic submucosal dissection (ESD); however, a useful biomarker for predicting recurrence is not available. The present study investigated whether the expression of CD44 variant 9 (CD44v9), a functional cancer stem cell marker, in the primary gastric cancer tissue represents an indicator of recurrence.

Methods: Eighty-eight patients who underwent ESD for EGC from 2008 to 2010 were enrolled and monitored for recurrence for 3 years. The expression levels of CD44v9 in the tissue of initial EGCs were evaluated by immunohistochemistry, and the recurrence rate was compared between CD44v9-positive and CD44v9-negative groups. The mucin phenotype and expression of microRNA-21 (miR-21) and programmed cell death protein 4 (PDCD4) were also analysed.

Results: The recurrence rate of EGC was significantly higher in the CD44v9-positive group than in the CD44v9-negative group (hazard ratio (HR), 21.8; 95% confidence interval (CI), 5.71-83.1). However, mucin phenotypes and the expression of miR-21 and PDCD4 did not predict recurrence after ESD. Meanwhile, grade of gastric atrophy was also identified as a significant marker of multiple recurrence (HR, 4.95; 95% CI, 1.30-18.8).

Conclusion: CD44 variant 9 expression represents a potential predictive marker for recurrence in EGC.

Figure 1

Study design. This study included 88 patients who underwent ESD for the treatment of EGCs at the Keio University Hospital between February 2008 and March 2010. Of a total of 88 ESD samples, 10 from patients who had a history of ESD and 4 from patients in whom multiple ESDs were performed simultaneously were excluded. Of the 74 initial samples in which ESD was performed, 3 from patients who had never undergone endoscopic examination after their initial ESD, 5 from patients who had gastrectomy because of a positive margin, and 1 from a patient who was treated with chemotherapy for oesophageal cancer that developed after ESD for EGC were excluded. During the follow-up period after ESD, development of multiple recurrence of EGCs were identified in 13 cases, and no recurrences were detected in the remaining 52 cases. Abbreviations: EGC=early gastric cancer; ESD=endoscopic submucosal dissection.

Figure 2

Histogram of CD44v9 IHC scores for all 65 EGCs. The x axis shows the CD44v9 IHC score (%) and the y axis shows the number of patients. Abbreviations: CD44v9=CD44 variant 9; EGC=early gastric cancer; IHC=immunohistochemistry.

Figure 3

Representative results of CD44v9 IHC in EGC. (A) CD44v9-negative EGC. (B and C) CD44v9-positive EGC. Inverse correlation between CD44v9 expression and phospho-p38^MAPK detection in EGC. Abbreviations: CD44v9=CD44 variant 9; EGC=early gastric cancer; IHC=immunohistochemistry.

Figure 4

Kaplan–Meier curves. (A–E) Kaplan–Meier curves for recurrence-free rate of EGC.(A) CD44v9-negative (dotted line, n=52) and CD44v9-positive (solid line, n=13) groups; (B) mucin phenotype: gastric phenotype (solid line, n=17), mixed phenotype (dotted line, n=23), and intestinal phenotype (dashed line, n=25) groups; (C) miR-21 expression: miR-21-lower (dotted line, n=27) and miR-21-higher (solid line, n=34) groups; (D) PDCD4 expression: PDCD4-lower (dotted line, n=27) and PDCD4-higher (solid line, n=38) groups; (E) type of gastric atrophy: closed-type (dotted line, n=36) and open-type (solid line, n=29) groups. Abbreviations: CD44v9=CD44 variant 9; EGC=early gastric cancer; ESD=endoscopic submucosal dissection; miR-21=microRNA-21; PDCD4=programmed cell death protein 4.