['To further evaluate the association between the cytoplasmic or nuclear localization of ErbB3 with biochemical recurrence (BCR) in patients with prostate cancer and positive surgical margins, as there is a greater risk of BCR for such patients after radical prostatectomy (RP).', 'We recently noted that ErbB3, which is normally associated with the plasma membrane, can translocate to the nucleus, an event which appears to be associated with disease progression. We evaluated ErbB3 expression and localization using immunohistochemistry on tissue samples from 55 patients with positive surgical margins after RP; 30 of these 55 (55%) had BCR after 3 years of follow-up. The relationship between ErbB3 nuclear localization and BCR (prostate-specific antigen, PSA, >0.3 ng/mL) after RP was analysed by Kaplan-Meier survival analysis and Cox regression models.', 'The BCR-free survival probability at 3 years was 0.65 and 0.35 for positive and negative nuclear ErbB3, respectively (Kaplan-Meier, P = 0.029). Patients negative for nuclear ErbB3 had a 2.47-fold increase in BCR frequency in a univariate Cox model (P = 0.008) and it remained an independent prognostic marker when combined with clinical prognostic variables in a multivariate model (P = 0.023).'] Does low nuclear ErbB3 predict biochemical recurrence in patients with prostate cancer?