Significant prognostic factor of immunohistochemical HER-2 expression using initial prostate biopsy specimens with M1b prostate cancer.

摘要

BACKGROUND: We examined whether human epidermal growth factor-2(HER-2) overexpression could be a useful marker of outcome after hormone therapy in patients with M1b prostate cancer (PC). SUBJECTS AND METHODS: The subjects were 102 patients who were diagnosed with M1b PC at Aichi Medical University Hospital. HER-2 expression was determined by immunohistochemical (IHC) staining using initial needle biopsy specimens for diagnosis. The results were classified into four grades (0, 1+, 2+, 3+), and scores of 1+ or greater were considered overexpression and defined as positive. RESULTS: The results showed a rating of 0 in 72 subjects, 1+ in 10, 2+ in 14, and 3+ in 6; 30 subjects (29.4%) were classified as HER-2 positive. Comparison of clinical data of HER-2 positive and negative subjects obtained at baseline revealed many of the subjects with high-grade tumors by Gleason score were HER-2 positive (P = 0.030). The prostate-specific antigen (PSA) relapse was observed in 76 subjects and cause-specific death occurred in 44. A significant difference was observed only in the item HER-2 (negative vs. positive) by multivariate Cox proportional hazard analysis. The 5-year PSA relapse-free rate was 0% in subjects with HER-2 positive (26/30), and 43.9% in subjects with HER-2 negative (50/72, P = 0.0192). The 5-year cause-specific survival rate was 40.9% in subjects with HER-2 positive (30/102), and 67.3% in subjects with HER-2 negative (72/102, P = 0.0301). CONCLUSION: HER-2 overexpression as determined by IHC staining using needle biopsy specimens for diagnosis with M1b PC is a significant prognostic factor for PSA relapse after hormone therapy and unfavorable outcome.