The significance of thymidylate synthase expression in non-small cell lung cancer tumor tissue

Abstract

Objective To explore the relationship among the thymidylate synthase (TS) level, age and different clinicopathologic features in human non-small cell lung cancer(NSCLC) tumor tissue. Methods The clinical data and operative specimens of 302 NSCLC patients were collected in Oncology of Beijing Chest Hospital from March 2008 to October 2009.TS protein expression was evaluated by semi-quantitative immunohistochemistry (IHC) in formalin-fixed paraffin-embedded (FFPE) specimens.Patients were divided into three groups: ≤45 years old group, the 46~69 age group, ≥70 years old group.IHC scores range was 0~9 points.Furthermore, according to the IHC score, patients were divided into two groups: low group (0~3 points) and high group(>3 points). TS expression rates in different groups were analyzed by χ2 test and the correlation analysis was conducted by Pearson correlation analysis. Results There were 140(46.4%) squamous cell carcinoma and 162(53.6%) non-squamous cell carcinoma patients in the total 302 cases.The rate of TS high expression in squamous cell carcinoma was 32.1% (45/140) while in non-squamous cell carcinoma was 29.0% (47/162) respectively, no significant difference was observed(χ2=0.35, P=0.556). TS high expression rates in different age groups were 45.2% (14/31), 31.7% (70/221) and 16.0% (8/50) respectively, and the difference was statistically significant (χ2=8.52, P=0.016). Two hundred and eighty-seven NSCLC patients had pathologic differentiation, TS high expression rates in poorly differentiated and well-differentiated tumor tissue were 37.8%(37/98) and 25.4%(48/189) respectively, the difference was statistically obvious (χ2=4.73, P=0.030). Correlation analysis showed that age was negatively correlated with the IHC scores(r=-0.15, P=0.010); IHC scores had no correlation with the degree of differentiation (r=-0.11, P=0.057). No significant difference was found in TS expression among pathological type, sex, smoking index, tumor size, TNM stage and lymph node metastasis(χ2=0.35, 0.85, 0.41, 0.01, 0.16, 0.16; P>0.05). Conclusion TS expression in NSCLC tumor′s tissue is relative to age as well as the degree of tumor differentiation, but it is only negatively correlated with age. Key words: Lung neoplasms; Carcinoma, non-small cell lung; Thymidylate synthase; Prognosis