Ki-67 labeling index as a prognostic marker in advanced stomach cancer

Purpose: Proliferation marker Ki-67 is widely used in cancer prognosis prediction.We tried to investigate the role of Ki-67 as a prognostic factor in stomach cancer after surgery in this study.Methods: We retrospectively evaluated 251 patients who underwent curative resection for gastric cancer from 2010 to 2015.In pathologic examination, Ki-67 labeling index was defined as the percentage of Ki-67 antigen positive cells.Prognostic significance of Ki-67 for gastric cancer was evaluated.Disease-free survival (DFS) was assessed as a primary end-point. Results:The median follow-up period was 28.0 months.Thirty-one patients (12.4%) showed Ki-67 labeling index (LI) lower than 25%.Sixty-eight patients (26.6%) showed recurrence during follow-up period.Recurrence was associated with Ki-67 LI level (≤25%, P = 0.016), and lymph node metastasis status (P = 0.002).High Ki-67 LI level (>25%) was also related to p53 positivity (P < 0.001) and poorly cohesive type (P = 0.002).The 3-year DFS was 69.4%.Low Ki-67 LI level (≤25%) was related with low DFS (47.6% vs. 72.6%,P = 0.016).T stage (P < 0.001), N stage (P = 0.006), lymphovascular invasion (P = 0.010), and neuronal invasion (P = 0.001) also affected the DFS.In addition, T stage (P = 0.03) and Ki-67 LI (P = 0.035) were independent prognostic factors for DFS.In patients treated with adjuvant chemotherapy (n = 239, 93.4%), low Ki-67 (≤25%) was a poor prognostic factor for DFS (P = 0.013).Conclusion: Low Ki-67 LI predicts high rate of progression and low DFS of stomach cancer.Ki-67 LI can be a predictive marker in resected stomach cancer treated with surgery and adjuvant chemotherapy.[