BACKGROUND: Gastric cancers with
microsatellite instabilities (MSI) have been reported to be associated with favorable
prognosis . However, the significance of the effect of MSI on the clinicopathological features, as well as its
association with
mucin phenotype , remains unclear.
METHODS: MSI status was assessed in 414 cases of
gastric cancer using
polymerase chain reaction analysis of five
microsatellite loci, as recommended by National
Cancer Institution criteria. The expression of
mucins (MUC5AC, MUC6, MUC2, and CD10) was assessed.
RESULTS: Out of 414 total cases of
gastric cancer , 380 (91.7%), 11 (2.7%), and 23 (5.6%) were
microsatellite stable (MSS), low-level MSI (MSI-L), and high-level MSI (MSI-H), respectively. Compared to MSS/MSI-L, MSI-H
gastric cancers were associated with older age (p=0.010),
tumor size (p=0.014), excavated gross (p=0.042), intestinal type (p=0.028), aggressive
behaviors (increase of T stage [p=0.009]), perineural invasion [p=0.022], and lymphovascular emboli [p=0.027]). MSI-H
gastric cancers were associated with
tumor necrosis (p=0.041),
tumor-infiltrating lymphocytes (> or =2/high
power field, p or =10% of mass, p=0.031),
tumor-infiltrating lymphocytes (p<0.001), intestinal type (p=0.014), and
gastric mucin phenotypes (p=0.020) could represent independent features associated with MSI-H
gastric cancers . MSI-H intestinal type
gastric cancers had a tendency for poor
prognosis in univariate
analysis (p=0.054) but no
association in Cox
multivariate analysis (p=0.197).
CONCLUSIONS: Our data suggest that MSI-H
gastric cancers exhibit distinct aggressive
biologic behaviors and a
gastric mucin phenotype . This contradicts previous
reports that describe MSI-H
gastric cancer as being associated with favorable
prognosis .