Clinical significance of Ki-67 and p53 expression in curatively resected non-small cell lung cancer

The aim of this study is to explore the association of Ki-67 and p53 expression with prognosis in non-small cell lung cancer (NSCLC) patients who underwent curative resection. We retrospectively identified 116 consecutive patients with stages I-III NSCLC who underwent curative resection at a single center from January 2007 to December 2012. Ki-67 and p53 expression was assessed by immunohistochemistry. Data on clinicopathologic features and survival were collected retrospectively. Ki-67 expression in 109 samples and p53 expression in 115 patients were analyzed. According to the results, 108 patients (99 %) showed at least some expression of Ki-67. The median Ki-67 expression level was 30 %. Positive p53 expression was observed in 91 (79 %) patients. Higher Ki-67 expression (>40 %) was significantly more frequent in male (26 vs. 4 % in female, p=0.002), ever-smoker (31 vs. 10 % in never-smoker, p=0.024), and non-adenocarcinoma (30 vs. 11 % of adenocarcinoma, p=0.012) patients. In univariable analysis, median disease-free survival (DFS) was shorter with higher Ki-67 expression (16.1 vs. 61.9 months in those with lower Ki-67 expression, p=0.005), and p53 expression did not show an association with DFS. Among 42 patients with stage I NSCLC who did not receive adjuvant chemotherapy, DFS was significantly worse in patients with higher Ki-67 expression (2-year DFS rate 57 vs. 88 %, p=0.018). In a Cox regression model, higher Ki-67 expression (>40 %) was a significant independent prognostic factor associated with poorer DFS (HR 2.9, 95 % CI 1.3-6.2) along with TNM stage and age. Higher Ki-67 expression (>40 %) showed an independent association with shorter DFS in NSCLC patients who underwent curative resection.