The loss of PTEN expression and microsatellite stability (MSS) were predictors of unfavorable prognosis in gastric cancer (GC).

The predictors for the prognosis of gastric cancer (GC) are not clear. We intended to explore the role of PTEN and microsatellite (MS) in GC, showing their potential as prognostic markers. Primary gastric cancer tissues, adjacent normal tissues, and clinicopathological parameters of 187 patients were collected. The expression level of PTEN and MS status were classified by immunohistochemistry (IHC). The relationship among indicators was compared by the chi-square test. The survival curves were delineated by Kaplan-Meier and tested by Log-rank methods. The impact of multiple factors on prognosis was determined by COX proportional hazards model. Significantly, PTEN expression was associated with lymphatic invasion (p = 0.011) and Lauren grade (p = 0.015). MS status was associated with differentiation (p = 0.006) and Lauren grades (p = 0.035). TNM stage was associated with MS status under positive PTEN expression (p = 0.014). Patients with microsatellite stability (MSS) had worse median overall survival (OS) than that with microsatellite instability (MSI) (p = 0.013). Patients with negative PTEN expression had a worse median OS than that with positive PTEN expression (p < 0.001). The tumor subtype of PTEN negative-MSS (p < 0.001) and PTEN negative-MSI (p = 0.042) were strong predictors of poor survival. Negative PTEN expression and MSS might lead to unfavorable prognosis due to their association with clinicopathological parameters of GC. PTEN expression and MS status could be predictors for the prognosis of GC.