B cells in the peritumor region of primary colorectal cancer and synchronous liver metastasis associate with longer survival

Purpose Prognostic value of local B-cells between normal colon mucosa (NM), primary colorectal cancer (pCRC) and its paired synchronous and metachronous liver metastasis (LM) is under investigation and is the subject of the present study. Methods Formalin-fixed paraffin-embedded tissue sections from NM, pCRC and synchronous (N = 55) or metachronous (N = 44) LM were stained immunohistochemically for B cells using anti-CD20 antibodies. Densities of B cells were assessed in NM, tumor center (TC), inner margin (IM), outer margin (OM) and peritumor area (PT) from pCRC and LM by using the QuPath software and assessed as prognostic variables for overall survival (OS). Results Density of B cells in the TC of pCRC were significantly smaller compared to NM in both synchronous and metachronous groups. OM and PT showed significantly greater cell densities vs TC and IM in pCRC and LM in both groups. TC and OM showed greater cell density in LM vs pCRC in both groups. High B cell densities in PT region of pCRC and LM and in IM of LM were associated with longer OS in synchronous group. Conclusions Smaller density of B cells in TC of pCRC was associated with CRC development. High infiltration of B cells in pCRC and in synchronous LM correlated with improved overall survival which may guide prognostic stratification.