After exclusion of 23 cases from Group 2, 222 cases underwent molecular investigations for MSI, KRAS and BRAF. The kinase inhibitor MEK162 aim of this study group was to determine the prognostic value of TOPK in CRCs, with subgroup analysis by KRAS and BRAF mutation. Multivariable cancer-specific survival time models were evaluated by including candidate variables such as age, sex, pT and pN classification, vascular invasion and MSI status. A total of 23 cases were excluded from Group 3 (Figure 1B). The remaining 71 Lynch syndrome-associated CRCs underwent molecular analysis for KRAS and BRAF. The association of TOPK expression with mutational status of KRAS and BRAF, clinicopathological features and cancer-specific survival time, was assessed.
One case of metastatic CRC was excluded from Group 4 because of insufficient material for adequate assessment of TOPK expression (Figure 1C). Immunohistochemistry for PTEN and molecular investigations of MSI, KRAS and BRAF were previously performed (Frattini et al, 2007). The prognostic and predictive value of TOPK in this group of patients was analysed, with specific end points of interest being cancer-specific survival time and objective tumour response to anti-EGFR agents. The use of all patient material was approved by local Ethics Committees. Statistical analysis methods Associations of TOPK with categorical features were investigated by Chi-Square and Fisher’s Exact tests where appropriate, and by Student’s t-test for age. Survival analysis was performed using the Kaplan�CMeier method, log-rank test and by multiple Cox regression analysis after verification of the proportional hazards assumption.
The appropriate number of variables to be included in regression models was dependent on the frequency of patient deaths in each analysis. We included 1 variable per 10 deaths, to prevent overfitting. Differences in TOPK expression between normal colonic mucosa and tumour were determined using Wilcoxon’s rank-sum test for medians. The most clinically relevant cutoff score for TOPK was determined on subgroup A by receiver operating characteristic (ROC) curve analysis for end point survival/death. To prevent overfitting, re-sampling of data was performed by bootstrapping 200 times. The inter-observer variability of TOPK staining was assessed using the intra-class correlation coefficient (ICC), with values of 0.8 indicating excellent agreement.
Missing clinicopathological data were assumed to be at random. No imputation was performed; rather, only patients with complete Dacomitinib data for all features were included in multivariable analyses. P-values <0.05 were considered to be statistically significant. Results TOPK expression in normal colon versus sporadic CRC T-cell-originated protein kinase expression in 57 normal colonic mucosa samples was compared with sporadic CRCs from Group 1 (n=1044).