Current knowledge makes it very difficult to predict which men will experience biochemical recurrence (BCR) after salvage radiation therapy (SRT) for recurrent prostate cancer (PCa). We are also lacking in novel targets for adjuvant therapies. At the College of Medicine, Mayo Clinic Florida, Jacksonville, FL., researchers evaluated the association of B7-H3 expression in primary PCa tumors and BCR after SRT.

They evaluated 148 men who received SRT between July 1987 and July 2003. Expression of B7-H3 in primary PCa tumors was detected using a staining method. The staining levels (which showed the presence of B7-H3 expression) were quantified via visual assessment and categorized as weak, moderate, or marked. Relative risks (RRs) and 95% confidence intervals (CIs) from Cox proportional hazards models were used to examine the association between B7-H3 staining and BCR.

*With a median follow-up of 6.2 years (minimum, 0.6; maximum, 14.7), 78 men (53%) experienced biochemical recurrence.

*In single-variable analysis, there was evidence of an increased risk of BCR for men with moderate (RR, 2.25; 95% CI, 1.24-4.09, p = 0.008) and marked (RR, 4.40, 95% CI, 2.29-8.43, p < 0.001) B7-H3 staining compared with weak staining.* This evidence remained, albeit weaker, after adjustment for additional clinicopathologic covariates (RR, 1.82, p = 0.068 [moderate vs. weak]; RR, 2.87, p = 0.003 [marked vs. weak]).This is the first evidence showing that higher tumor B7-H3 staining in a primary prostate cancer tumor is associated with increased risk of BCR after SRT. We will need to have additional future studies with a larger sample to validate these results. We will also need to explore if targeting B7-H3 could be positive in an adjuvant setting.Reference: Int J Radiat Oncol Biol Phys. 2010 Jul 1. Epub ahead of print. doi: 10.1016/j.ijrobp.2010.01.061; Parker AS, Heckman MG, Sheinin Y, Wu KJ, Hilton TW, Diehl NN, Pisansky TM, Schild SE, Kwon ED, Buskirk SJPubMed Abstract PMID: 20598810Joel T Nowak, M.A., M.S.W.