PTEN Loss with ERG Negative Status is Associated with Lethal Disease after Radical Prostatectomy.

ABSTRACT

PURPOSE: Few groups have investigated the combined effects of PTEN loss and ERG expression on the outcomes of metastasis of or death from prostate cancer in surgically treated patients. We examined the association of PTEN/ERG status with lethal prostate cancer in patients treated with radical prostatectomy. MATERIALS AND METHODS: Included in analysis were 791 patients with clinically localized prostate cancer treated with radical prostatectomy at a single institution. Genetically validated immunohistochemistry assays for PTEN and ERG were performed on tissue microarrays. Multivariable Cox proportional hazard models were used to assess the association of PTEN/ERG status with lethal prostate cancer (defined as metastasis or prostate cancer specific death), adjusting for patient age, race, pathological grade and stage, and surgical margin status. RESULTS: Median followup in the cohort was 12.8 years. Of 791 cases 203 (25%) demonstrated PTEN loss and 330 of 776 (43%) were ERG positive. On multivariable analysis PTEN loss (HR 1.9, 95% CI 1.2-3.0, p=0.012) but not ERG expression (HR 0.6, 95% CI 0.4-1.1, p=0.11) was associated with an increased risk of lethal prostate cancer. The association of PTEN loss with lethal disease only remained among men with ERG negative tumors (HR 2.3, 95% CI 1.3-4.1, p=0.005) and not ERG positive tumors (HR 1.1, 95% CI 0.6-2.1, p=0.81). CONCLUSIONS: PTEN loss is associated with an increased risk of lethal prostate cancer after radical prostatectomy and this risk is most pronounced in the subgroup of patients with ERG negative tumors. This work corroborates the use of PTEN and ERG status for risk stratification in surgically treated patients.