PTK-7 Expression in Gastric Cancer: A Prognostic Determinant

BACKGROUND: Protein tyrosine kinase-7, a regulatory protein in the Wnt signaling pathway, was highly overexpressed in various cancer types and assumed to be related to prognosis. AIMS: The purpose of this study is to assess whether protein tyrosine kinase-7 expression status in curatively resected gastric carcinoma would independently identify patients with a high risk of recurrence and death. STUDY DESIGN: Retrospective cohort study. METHODS: We included patients who were at least 18 years of age and diagnosed with gastric cancer. The exclusion criterion was a metastatic disease at the time of diagnosis or operation. Data on clinicopathological prognostic determinants and clinical courses, including the date of disease relapse and survival status, were collected with the use of medical records. Surgically removed tumor tissue specimens were examined by two independent pathologists at the pathology department of our institution. Protein tyrosine kinase-7 expression status was assessed with immunohistochemical processing and stratified on a scale ranging from 0 to +3 according to the extent of stained tumor cells. It was then further categorized into two groups, one being + (positive), including +1, +2, and +3 scores, another was-(negative), including-and +/− scores. RESULTS: A total of 114 patients were analyzed. Protein tyrosine kinase-7 expression was present in 66.7% of the surgical tumor specimens. There was no statistically significant difference in almost all relevant parameters between the protein tyrosine kinase-7 positive and negative groups. The estimated median survival in the protein tyrosine kinase-7 positive group was significantly better than the protein tyrosine kinase-7 negative group (60 vs 22 months, p<0.001). Disease-free survival was found to be 55 months in the protein tyrosine kinase-7 positive group, whereas it was 21 months in the negative group (p=0.015). In the multivariate analysis, along with negative protein tyrosine kinase-7 expression, poor performance status, and advanced stage were significantly associated with the risk of death (p<0.001 for each). CONCLUSION: Compared to patients with negative PTK-7 expression, patients with positive PTK-7 expression have better disease-free survival and overall survival rates. Efforts should be made to enhance this finding and translate it into clinical practice.