Nuclear and cytoplasmic expression of ErbB-4 in prostate cancer

Purpose: To evaluate cytoplasmic and nuclear ErbB-4 expression in prostate cancer specimens and its association with outcome. Basic procedures: Specimens of 50 prostate cancer patients were investigated for ErbB-4 overexpression using immunohisto-chemistry staining. Cytoplasmic and nuclear staining was graded as 0-3 according to its intensity. The prognostic parameters were tumor stage, PSA level, Gleason score, probability of positive lymph nodes (Partin's tables and Roach equation), and 5-year disease free survival (Kattan nomogram). Main findings: Overexpression of ErbB-4 (≥1) was detected in 30 (60%) patients and overexpression using cytoplasmic and nuclear staining was ≥2 in 19 (38%) and 17 (34%) patients, respectively. In only one third of the specimens was there any similarity between the 2 types of staining. Advanced tumor stage, high pretreatment PSA levels and high Gleason scores were evenly distributed among the patients with low (≤1) and intermediate/high (≥2) ErbB-4 expression. The probability of lymph node involvement and 5-year disease free survival were similar in both types of staining. Principal conclusions: ErbB-4 was overexpressed (cytoplasmic and nuclear staining) in approximately one third of prostate cancer patients. The rate of similarity between the 2 staining types was only 33%: overexpression was evenly distributed among intermediate/high and low risk prostate cancer patients with both staining methods.