Abstract Background Prostate Stem Cell Antigen (PSCA) is frequently expressed in prostate cancer but its exact function is unclear. Methods To clarify contradictory findings on the prognostic role of PSCA expression, a tissue microarray containing 13,665 prostate cancers was analyzed by immunohistochemistry. Results PSCA staining was absent in normal epithelial and stromal cells of the prostate. Membranous and cytoplasmic PSCA staining was seen in 53.7% of 9642 interpretable tumors. Staining was weak in 22.4%, moderate in 24.5% and strong in 6.8% of tumors. PSCA expression was associated with favorable pathological and clinical tumor features: Early pathological tumor stage (p < 0.0001), low Gleason grade (p < 0.0001), absence of lymph node metastasis (p < 0.0001), low pre-operative PSA level (p = 0.0118), negative surgical margin (p < 0.0001) and reduced PSA recurrence (p < 0.0001). PSCA expression was an independent predictor of prognosis in multivariate analysis (hazard ratio 0.84, p < 0.0001). Conclusions The absence of statistical relationship to TMPRSS2:ERG fusion status, chromosomal deletion or high tumor cell proliferation argues against a major role of PSCA for regulation of cell cycle or genomic integrity. PSCA expression is linked to favorable prognosis. PSCA measurement is a candidate for inclusion in multi-parametric prognostic prostate cancer tests.
