Pretreatment serum level of HER2/nue as a prognostic factor in metastatic prostate cancer patients about to undergo endocrine therapy

Abstract

Overexpression of the HER2 receptor protein and amplification of the HER2 gene has been implicated in tumor development and progression, and has been associated with a poor prognosis in several types of cancer. The aim of this study was to evaluate whether pretreatment serum HER2 levels can be used to predict biochemical recurrence-free survival in prostate cancer patients about to undergo endocrine therapy. The study population consisted of 379 untreated patients with histologically diagnosed prostate cancer: 197 with T2N0M0, 93 with T3N0M0, 19 with TxN1Mx, and 70 with TxNxM1. Serum HER2 levels were assessed in the prostate cancer patients prior to treatment as well as in a control group of 100 patients with histologically confirmed non-cancer. Biochemical recurrence-free curves for the patients were investigated separately using the Kaplan-Meier method. The mean level of HER2 in serum was significantly higher in prostate cancer patients than non-prostate cancer patients (P = 0.006). Also, the serum HER2 level was significantly higher in bone metastatic cancer patients (14.3 +/- 6.3 ng/mL) than in non-metastatic patients (T2: 11.9 +/- 2.3 ng/mL, P = 0.003; T3: 12.2 +/- 2.8 ng/mL, P = 0.011). The metastatic patients were divided into those with low and high HER2 levels using a cutoff value of 12.6 ng/mL based on receiver-operating characteristic curves. The biochemical recurrence-free rate was significantly poorer in patients with a high HER2 level (P = 0.0078, log-rank test). Multivariate Cox logistic regression analysis demonstrated that the pretreatment serum HER2 value (P = 0.022), serum prostate-specific antigen value (P = 0.018), and extent of disease score (P = 0.027) were independent predictors of recurrence. The pretreatment serum HER2 level may be a useful independent prognostic factor that is associated with a high risk of biochemical recurrence in metastatic prostate cancer patients about to undergo endocrine therapy.