Radiotherapy After Radical Prostatectomy: Adjuvant Versus Salvage Approach

Introduction

Over 200,000 men are expected to have been diagnosed with prostate cancer in 2014. Approximately one-third will undergo radical prostatectomy and one-third of these men will have a positive margin. Another 10% are likely to have seminal vesicle invasion. Other variables that increase the patient’s risk for recurrence include high Gleason score, extracapsular extension, positive lymph nodes, and preoperative prostate-specific antigen (PSA). Some patients may also recur without those features. The potential benefit of adjuvant irradiation has been studied prospectively in men with extracapsular extension, positive surgical margins, and positive seminal vesicles. Despite level one evidence suggesting that adjuvant radiotherapy be offered to all those with high-risk features, its use has still not gained widespread acceptance among urologists. This may be due in part to concern over design flaws in the randomized trials as well as the belief that early salvage irradiation is comparable. Salvage radiotherapy has also been shown to be beneficial albeit without a randomized trial.

Whether used in the adjuvant or salvage setting, the potential benefit of irradiation is based on the premise that there is residual microscopic disease in the prostatic fossa and that this disease can be eradicated with local radiation. In the true adjuvant setting, there is no evidence of residual disease, but the patient is at significant risk of recurrence based on the high-risk features delineated earlier. In the salvage setting, the disease is known to be recurrent, usually only by biochemical relapse although new imaging modalities may be capable of demonstrating clinically apparent disease. Often the challenge is determining which men also have micrometastatic disease.

While the prospective randomized controlled trials (RCTs) comparing adjuvant versus salvage radiotherapy are pending, nomograms may be useful in assisting urologists and radiation oncologists help their patients make appropriate choices. New imaging techniques are evolving, such as dynamic contrast enhanced MRI, choline PET CT and fluoride bone scans, that may provide additional useful clinical information in these difficult cases.