Prostate-specific antigen doubling time is a significant predictor of overall and disease-free survival in patients with prostate adenocarcinoma treated with brachytherapy

Recently, new approaches have been implemented in treating patients with newly diagnosed metastatic prostate cancer (PCa). An interesting area of study is to determine which risk factors may be used as predictors of more aggressive PCa behavior in patients with biochemical failure. The aim of this study was to determine prognostic factors in patients with prostate-specific antigen (PSA) failure after undergoing brachytherapy.

Between 1990 and 2015, 2771 patients with localized PCa underwent treatment at our institution treated by a single radiation oncologist with low-dose-rate brachytherapy as a component of definitive radiation therapy. Disease-specific survival (DSS), distant metastases (DM), and overall survival were calculated by the Kaplan-Meier method. Multivariable Cox regression analysis was also performed.

In this group, 2126 patients (89%) had no evidence of PSA failure. Of the 251 of patients that did have biochemical failure, 115 (45.8%), 58 (23.1%), 78 (31.1%) had a PSA doubling time (PSADT) of <6 months, 6-12 months, and >12 months, respectively. Doubling time was associated with a statistically significant impact on DSS and DM but not overall survival, which appears to be dominated by initial age at diagnosis as well as stage.

We have shown here that PSADT predicts for DSS and freedom from DM in our large prospectively followed cohort. Given the variable trajectory of metastatic and recurrent PCa, strong prognostic factors such as PSADT may be able to select a group of patients who benefit from earlier or escalated systemic therapies such as androgen deprivation or cytotoxic chemotherapy.

Brachytherapy. 2018 Jul 27 [Epub ahead of print]

Lucas Resende Salgado, Ryan Rhome, William Oh, Nelson Stone, Richard Stock

Department of Radiation Oncology, Mount Sinai Hospital, New York, NY. Electronic address: ., Indiana University, Department of Radiation Oncology, Simon Cancer Center, Indianapolis, IN., Division of Hematology and Medical Oncology, Mount Sinai Hospital, New York, NY., Department of Urology, Mount Sinai Hospital, New York, NY., Department of Radiation Oncology, Mount Sinai Hospital, New York, NY.