PSCA expression is associated with favorable tumor features and reduced PSA recurrence in operated prostate cancer

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.