Plasma levels of interleukin-6 and its soluble receptor are associated with prostate cancer progression and metastasis

Objectives. Elevated circulating levels of interleukin 6 (IL-6) have been associated with cancer metastasis. IL-6 binds either to membrane or to soluble IL-6 receptor (IL-6sR), which then induces homodimerization of gp130 that activates downstream signaling. We tested the hypothesis that preoperative plasma IL-6 and IL-6sR levels are associated with prostate cancer stage, progression, and metastasis after radical prostatectomy. Methods. Plasma levels of IL-6 and IL-6sR were measured in 120 consecutive patients who underwent radical prostatectomy for clinically localized prostate cancer, 44 healthy men without any cancer, 19 men with prostate cancer metastatic to the regional lymph nodes, and 10 men with prostate cancer metastatic to bone. Results. Plasma IL-6 and IL-6sR levels were highest in patients with bone metastases ( P