Neutrophil infiltrations correlate very strongly (r > 0.7) with C3AR1 in 17 cancer types and strongly in 13 cancer types; macrophage infiltrations correlate very strongly (r > 0.7) with C3AR1 in 16 cancer types and correlate strongly (r = 0.5~<0.7) with C3AR1 in six cancer types (SKCM, SKCM-Metastasis, STAD, PRAD, LUSC, and KIRP); and B-cell infiltrations correlate strongly (r = 0.5~<0.7) with C3AR1 in 11 cancer types (UCEC, LICH, THCA, BRCA-Luminal, CHOL, KICH, KIRP, LGG, PRAD, THCA, and THYM). This evidence concerns the gene C3AR1 and cancer.