较高水平 TIL（肿瘤浸润淋巴细胞）（TILs）与更好预后相关，而 CDK5 在非转移性和转移性结肠癌中发挥不同作用

We investigated the prognostic value of cyclin-dependent kinase 5 (CDK5) in a true population-based cohort of patients with colon cancer.

1. Immunohistochemical (IHC) staining was used to retrospectively analyse the expression of CDK5 in colon cancer tissue samples of 296 patients. The 2 test, Kaplan-Meier method and Cox proportional regression model were used to analyse the difference between the patients with differential expression of CDK5 and with different stages (metastatic and nonmetastatic); 2. The number of tumour-infiltrating lymphocytes (TILs) in tumour sections was determined, and its relationship with prognosis was explored.

1. Among 296 patients stained for CDK5, 18 cases (6.09%) showed negative expression, 77 cases (26.01%) showed weak expression (+1), 124 cases (41.89%) showed medium positive expression (2+), and 77 cases (26.01%) showed strong positive expression (3+). The expression of CDK5 was neither related to mismatch repair nor TILs ( p > .05 ). In non-metastatic patients, longer progression-free survival (PFS) and cancer-specific survival (CSS) were observed in patients with high CDK5 expression (2+ or 3+) than low CDK5 expression (- or 1+), while in metastatic disease, the opposite was true ( p < .001 ). 2. TILs in 226 patients were detected in the study. Among them, 115 cases (50.88%) showed a low number of TILs (TILs-L), and 111 cases (49.12%) showed a high number of TILs (TILs-H). Patients with a TIL ratio greater than .2 had a significantly better CSS ( p < .001 ) or PFS ( p = .008 ) than patients with a lower TIL ratio. By multivariate analysis, TILs-H was a protective factor for CSS, however failed to reach a significant difference (hazard ratio: .59, 95% CI: .33 1.06, p = .079 ), and so was the PFS (HR: .65, 95% CI: .29 1.43, p = .279 ).

High expression of CDK5 indicates a good prognosis in nonmetastatic colon cancer, while it is the opposite in metastatic colon cancer, and the expression of CDK5 is unrelated to TILs. Patients with TIL-H have a better prognosis, with a proper cut-off value of 20% for colon cancer.