Aims: Assess CD8 positive TILs in CRC patients.
Methods: Tissue microarrays (TMAs) were assembled from formalin-fixed tissue in 77 randomly selected sporadic CRC cases, previously classified as MSI-H (high), MSI-L (low) and MSS (stable). Sections were stained immunohistochemically using an anti-CD8 T cell antibody. The number of CD8+ T lymphocytes (CD8+ TILs) within tumour epithelium was assessed by counting the area of each tissue core under high-power field (x40 objective). The results were correlated with age, gender, & standard pathological parameters including Dukes stage, TNM stage, lymphovascular & neural invasion and MSI status.
Results: A statistically significant correlation (p=0.03) was noted between CD8+TILs and Dukes stage. CD8+TILs (median 6.5, range 1.4–15.8) were higher in Dukes A and B, than in Dukes C and D (median 2.7, range 0.3–15.4). Although CD8+TILs were greater in MSI-L & MSI-H tumours (n=10) compared to MSS tumours (n=67), with a mean rank value of 46.10 vs. 37.94, this was not statistically significant (p=0.28).
Conclusions: Early stage colorectal cancer is associated with an increase number of CD8+TILs. Higher CD8+TILs were observed in MSI+ colorectal cancer but this was not statistically significant.
