Prognostic value of Ki-67 in non-metastatic colorectal adenocarcinoma: a retrospective study

Abstract Background Ki-67 is a cellular proliferation marker with an established prognostic role in several types of human tumors, whereas its prognostic significance in colorectal cancer remains uncertain. We assessed its prognostic value in an independent retrospective cohort of patients with non-metastatic colorectal adenocarcinoma. Methods Overall survival (OS) and disease-free survival (DFS) were analyzed using Kaplan–Meier survival analysis and Cox proportional hazards regression, both in the overall cohort and stratified according to adjuvant therapy. Results Among 207 cases, 132 (63.8%) and 75 (36.2%) showed high (≥ 50%) and low (< 50%) Ki-67, respectively. Kaplan–Meier analysis showed no significant differences in OS according to Ki-67 status ( p = 0.158), whereas DFS differed significantly ( p = 0.032). Fifteen-year DFS was 59% in the high Ki-67 group compared with 46% in the low Ki-67 group. In stratified multivariable Cox regression analysis, higher Ki-67 was significantly associated with a lower hazard of a DFS event among patients receiving adjuvant therapy (hazard ratio per 1-percentage-point increase = 0.954, 95% confidence interval: 0.925–0.984; p = 0.003). Conclusions In patients with non-metastatic colorectal adenocarcinoma receiving conventional adjuvant therapy, low Ki-67 (< 50%) may identify a subgroup with significantly shorter DFS.