The prognosis of stage I non-small cell lung cancer (NSCLC) is generally good. However, some of the stage I NSCLC patients still may have early recurrence and metastasis, and there is no standard method to screen this part of the population. The aim of this study is to investigate the relationship between Ki67 expression as well as epidermal growth factor receptor (EGFR) mutation and the risk of recurrence in postoperative patients with stage I lung adenocarcinoma.
We retrospectively enrolled 118 postoperative patients with stage I lung adenocarcinoma. EGFR mutation was tested using amplification refractory mutation system polymerase chain reaction (ARMS-PCR) , and Ki67 level was detected by immunohistochemistry (IHC), followed by the collection of the patients’ clinical characteristics. Kaplan-Meier method, Log-rank test, and Cox proportional hazards regression model were used for the prognostic statistical analysis.
Among the 118 patients, the rate of high Ki67 expression was 43.22% (51/118), which is related to gender, smoking status, surgical method, differentiation degree, and postoperative stage (P<0.05). Meanwhile, EGFR mutation rate was 61.02% (72/118), of which EGFR exon 19 deletion mutation rate was 19.49% (23/118), and the EGFR exon 21 L858R mutation rate was 41.53% (49/118). However, Ki67 expression was not associated with EGFR mutation status (χ2=1.412, P=0.235). Survival analysis showed that high Ki67 expression was inversely associated with disease-free survival (DFS) and overall survival (OS) in stage I lung adenocarcinoma (P0.05). In the subgroup analysis, the DFS of the EGFR exon 19 deletion group was significantly decreased compared with the EGFR exon 21 L858R mutation group (P=0.031), but there was no significant difference in OS (P=0.308). Multivariate analysis showed that there was statistical significance between Ki67 expression (P=0.001) and DFS in stage I lung adenocarcinoma; Ki67 expression (P=0.03) and gender (P=0.015) were associated with OS in stage I lung adenocarcinoma.
Ki67 expression is an independent influencing factor for postoperative recurrence and OS of stage I lung adenocarcinoma and it is not significantly associated with EGFR mutation. There is no significant difference between EGFR mutation status and the prognostis of stage I lung adenocarcinoma. However, the prognosis differed in EGFR mutation types; the patients with EGFR exon 19 deletion are at higher risk of recurrence than EGFR exon 21 L858R mutation.