WASHINGTON, DC USA (UroToday.com) - According to this fascinating report, there is suggestion that localized prostate cancer may initiate osteolytic bone activity well before clinically apparent bone metastasis from prostate cancer occur.
As background, the receptor activator of NFkappaB Ligand (RANKL) pathway mediates interactions of tumor cells and the bone microenvironment. Both osteoblasts and bone marrow stromal cells secrete RANKL. This promotes osteolysis and development of bone metastases via activation of the RANK receptor on osteoclasts. RANKL and osteoprotegerin (OPG) are also expressed from tumor cells, further contributing to the cycle of bone metastasis. These investigators hypothesized that changes in RANKL and OPG are notable in the serum and bone marrow of patients with clinically localized prostate cancer without manifest bone metastases.
They measured concentrations of total sRANKL and OPG in serum and bone marrow specimens of 20 patients undergoing radical prostatectomy for localized prostate cancer and 9 individuals without prostate cancer using an enzyme linked immunosorbent assay. Ratios of sRANKL/OPG were calculated. Disseminated tumor cells (DTC) in bone marrow were determined by cytokeratine immunocytochemistry. Values were compared and correlated to clinical data.
The median values of serum sRANKL, OPG and ratio for prostate cancer and non-prostate cancer patients were 33515, 62, 840 and 131, 63, 2, respectively. Serum and corresponding bone marrow values of all 3 investigated parameters correlated significantly for sRANKL, OPG and ratio. Concentrations of sRANKL and OPG in bone marrow and serum were independent of Gleason score and PSA levels. What one wouldn’t expect was that patients with locally advanced prostate cancer (>pT2) had lower serum sRANKL levels than those with organ-confined disease. The presence of DTCs did not significantly affect sRANKL and OPG in bone marrow and serum. These data suggest that osteolytic activity may be initiated in patients with localized prostate cancer before bone metastases are clinically apparent.
Presented by Christian Schwentner, et al. at the American Urological Association (AUA) Annual Meeting - May 14 - 19, 2011 - Walter E. Washington Convention Center, Washington, DC USA
Reported for UroToday by Christopher P. Evans, MD, FACS, Professor and Chairman, Department of Urology, University of California, Davis, School of Medicine.