Detailed analysis of inflammatory cell infiltration in colorectal cancer

BACKGROUND: Higher-grade inflammatory infiltrate is a promising marker for better prognosis in colorectal cancer (CRC). However, the knowledge on the interrelationships between different inflammatory cells and classifications is fragmentary. METHODS: We analysed the densities of eight types of inflammatory cells in a prospectively recruited group of 117 CRC patients and determined their interrelationships and contributions to Klintrup–Mäkinen (K–M) score of overall peritumoural inflammation. We characterised the inflammatory infiltrate in relation to stage and recurrences in 24-month follow-up. RESULTS: There were high positive correlations between the inflammatory cell densities, with the exception of mast cells and CD1a(+) immature dendritic cells. High K–M score associated with high peri- and intratumoural densities of CD3(+), CD8(+), CD68(+), CD83(+), and FoxP3(+) cells and neutrophils. Advanced stage associated with low K–M score, as well as low CD3(+), CD8(+), CD83(+), and FoxP3(+) cell counts, of which low K–M score, low CD3(+) T-cell count, and low FoxP3(+) T-cell count were linked to higher recurrence rate. CONCLUSION: The density of CRC inflammatory infiltrate declines as stage advances. Especially, low K–M score and low T-cell counts predict higher recurrence rate. The high positive correlations between the individual inflammatory markers support the value of overall inflammatory reaction scoring.