Purpose: We evaluated the immunological response in patients with hormone sensitive and refractory prostate cancer, and untreated benign prostatic hyperplasia (BPH).
Materials and methods: Serum levels of pro-inflammatory and anti-inflammatory cytokines were measured by enzyme-linked immunosorbent assay in 3 groups of patients. The groups included 18 men with a mean age of 79 years who had hormone sensitive prostate cancer, mean prostate specific antigen (PSA) plus or minus standard deviation 1.03 +/- 2.65 ng./ml. and a mean of 35 months of treatment, 10 with a mean age of 86 years who had hormone refractory prostate cancer, mean PSA 27.52 +/- 42.23 ng./ml. and a mean of 42 months of treatment, and 19 with a mean age of 73 years who had BPH and mean PSA 3.37 +/- 2.47 ng./ml. Results were compared with those in 10 age matched, disease-free controls. In the hormone sensitive group PSA regressed to normal and there was clinical evidence of a response to hormone ablation therapy, including orchiectomy, luteinizing hormone releasing hormone analogue and androgen blockade. Hormone refractory cases had elevated PSA and/or clinical evidence of disease progression.
Results: Levels of the anti-inflammatory cytokines interleukin (IL)-4, IL-6 and IL-10 were significantly elevated in the hormone refractory group compared with values in the hormone sensitive group (p = 0.02, 0.01 and 0.0001, respectively). Abnormal anti-inflammatory cytokines in hormone resistant cases correlated with elevated PSA, while in the BPH group there was no significant difference from controls. Pro-inflammatory cytokines in the hormone sensitive and resistant groups were not significantly different from those in controls.
Conclusions: Our study indicates that in hormone refractory prostate cancer a high level of the anti-inflammatory cytokines IL-4, IL-6 and IL-10 develops that is directly associated with elevated PSA. Changes in the level of anti-inflammatory cytokines when androgen independent cells exist may have an important role in the selection of a subset of hormone insensitive cells. These criteria may be used as a prognostic marker for the response to hormone ablation therapy in men with prostate cancer.