CD4 and peritoneal neoplasm: Compared with primary peritoneal neoplasms group, the percentages of CD45 + PD-1 + lymphocytes, CD3 + PD-1 + T cells, and CD3 + CD4 + PD-1 + T cells were increased in the secondary peritoneal neoplasms group (the p value was respectively 0.010, 0.044, and 0.040), while PD-1 did not correlate with the primary sites in secondary group (P > 0.05).