Figure 2.

Higher CD45 expression in rectal cancer epithelial cells confers a poor therapeutic response to preoperative CRT. (A) A total of 44 pretreatment paraffin-embedded tissue samples obtained from patients with locally advance distal rectal cancer were subjected to immunofluorescence staining for CD45 and EpCAM to determine the relevance of CD45 expression in cancer cells to clinical outcome. The extent of therapeutic response to CRT was pathologically evaluated according to the AJCC TRG scoring. TRG 0 (complete response) and -1 (near complete response) were considered good responses, while TRG 2 (partial response) and -3 (poor or no response) were considered poor responses. Representative immunofluorescence images from the good responder (TRG 0-1) and poor responders (TRG 2-3) groups are presented in the left panel. H&E counterstaining was used to distinguish normal and tumor regions. The CD45 expression levels were scored based on the ratio of the colocalized area (EpCAM+CD45+) within the entire cancer epithelial cell area (EpCAM+) using Image-Pro Premier 9.0 software (Media Cybermetics, right panel, 3-5 spots/sample). The CD45^high and CD45^low groups were divided by the mean ratio of the colocalized area (EpCAM+CD45+) within the epithelial cells (mean value=0.16096±0.24376; high: n = 16, low: n = 28). The correlation between CD45 expression and TRG was analyzed using the χ2 test. (B) The multivariate analysis of recurrence-free survival indicated that the CD45 expression level in rectal cancer epithelial cells was significantly associated with shorter recurrence-free survival in 44 patients (hazard ratio 2.090; 95% confidence interval 1.121-3.897; p=0.020, upper panel). Kaplan-Meier plots also show the recurrence-free (lower left) and disease-specific (lower right) survivals of 44 patients with rectal cancer treated with preoperative CRT followed by surgical resection, according to the CD45 expression levels in primary tumor epithelial cells (p=0.022 and p=0.08, respectively).