The prognostic and clinicopathological roles of microsatellite instability, PD-L1 expression and tumor-infiltrating leukocytes in familial adenomatous polyposis

Abstract

Background: Microsatellite instability, programmed death-ligand 1 and tumor-infiltrating leukocytes are prognostic biomarkers in colorectal cancer but unknown toward familial adenomatous polyposis.

Aim: To investigate the prognostic and clinicopathological roles of microsatellite instability, programmed death-ligand 1 and tumor-infiltrating leukocytes in familial adenomatous polyposis.

Methods: Clinical data and paraffin embedded tissues from 45 familial adenomatous polyposis patients were collected. Microsatellite instability was detected by immunohistochemistry and polymerase chain reaction. Programmed death-ligand 1 was detected by immunohistochemistry. Tumor-infiltrating leukocytes comprising CD8⁺ T cells, M1 and M2 tumor associated macrophages, CD56^bright and CD56^dim natural killer cells were analyzed using multiple fluorescence immunohistochemistry.

Results: Microsatellite instability high was noted in 6 samples but not associated with overall survival or progression-free survival. Programmed death-ligand 1 is negative on tumor cells but positive on tumor-infiltrating leukocytes, and positive programmed death-ligand 1 expression on tumor-infiltrating leucocytes is associated with overall survival. Low CD56^bright natural killer cell infiltration was associated with longer progression-free survival and was an independent prognostic factor in FAP.

Conclusion: For familial adenomatous polyposis, microsatellite instability high can be found but has no correlation with prognosis; programmed death-ligand 1 on tumor-infiltrating leukocytes is related with overall survival; CD56^bright natural killer cell is an independent prognostic factor associating with longer progression-free survival.

Keywords: Familial adenomatous polyposis; Microsatellite instability; Natural killer cell; Programmed death-ligand 1; Tumor-infiltrating leukocytes.