Prognostic assessment of T‐cells in primary colorectal cancer and paired synchronous or metachronous liver metastasis

Prognostic value of T-cells between primary colorectal cancer (pCRC) and its paired synchronous and metachronous liver metastasis (LM) is underinvestigated and is the subject of the present study. We enrolled into this retrospective cohort study patients, who underwent resection of both pCRC and synchronous LM (N = 55) or metachronous LM (N = 44). After immunohistochemical staining for CD3+, CD8+, and CD45R0+ whole slides were scanned and T-cell densities were quantified using QuPath software in tumor center (TC), inner margin (IM), outer margin (OM), and peritumor zone (PT) of pCRC and LM. High densities of CD8+ T-cells in TC, OM and PT of synchronous LM were associated with longer disease-free survival (DFS). Greater densities of CD3+ T-cells in IM and PT and CD8+ T-cells in IM, OM and PT in synchronous LM over pCRC were associated with longer DFS. Greater densities of CD8+ T-cells in the TC and IM and CD3+ T-cells in the IM of pCRC were found in the metachronous over synchronous group. The first novel finding demonstrated that high density of CD8+ T cells in synchronous LM were associated with favorable outcome. The second finding of high CD8+ cell density in pCRC in metachronous over synchronous CRC may provide a mechanistic basis for the delay of metastatic spread. Both findings could be applied clinically with own reference values.