In serum samples, CCL2 concentration at the time of diagnosis, as assayed by enzyme-linked immunosorbent assay, was significantly higher in patients with prostate cancer compared with benign prostatic hyperplasia (median difference 0.22 ng/mL, 95% CI, 0.17–0.30) (p < 0.0001) and normal controls (median difference 0.13 ng/mL, 95% CI, 0.13–0.17) (p < 0.0001). The gene discussed is CCL2; the disease is prostate cancer.