HER-2 Expression in Secondary Circulating Prostate Cells does not Increase Risk of Biochemical Failure after Radical Prostatectomy for Prostate Cancer

Introduction: There is evidence linking HER-2 expression in prostate cancer to disease progression and the development of androgen independent disease. HER-2 expression increases after androgen blockade and is associated with increased prostate cancer specific mortality. We present the effect of HER-2 expression in circulating prostate cells (CPCs) on the risk of biochemical failure and its association with standard clinic-pathological parameters. Methods and patients: Blood samples were taken 4 monthly after radical prostatectomy to detect CPCs using anti-PSA and standard immunocytochemistry. Samples positive for CPCs underwent analysis for HER-2 expression using the HercepTest® kit. Standard clinicopathological parameters were recorded. Kaplan Meier plots determined the different biochemical failure free survival curves. Results: 92 biochemical failure free men participated, 37/92(40.2%) of men had secondary CPCs detected. Biochemical failure was significantly more frequent in men CPC positive than those CPC negative (p=0.001). The expression of HER-2 in secondary CPCs did not increase biochemical failure free survival in comparison with men CPC (+) HER-2 (-). Conclusion: In men without biochemical failure the expression of HER-2 positive CPCs did not increase the risk of developing biochemical failure.