Retrospective analysis of prognostic value of intratumoral immune infiltrate in patients with stage II or III colorectal cancer

Tumor-infiltrating CD8⁺ cytotoxic T cells confer favorable prognosis in colorectal cancer (CRC). The added prognostic value of other infiltrating immune cells is unclear. Retrospective pooled analysis of two prospective trials (SCOT and QUASAR 2) found that among patients with stage II or III CRC intraepithelial CD8 (CD8^IE) level was strongly prognostic for recurrence-free interval, as was intrastromal FoxP3 (FoxP3^IS). Association of other markers (CD20⁺ and CD68⁺) with recurrence-free interval were moderate. Compared with either marker alone, a composite marker including both CD8^IE and FoxP3^IS was superior when assessed as continuous variable. The authors conclude that combined evaluation of CD8^IE and FoxP3^IS could help to refine risk stratification in colorectal cancer.