Overview of Tumor Control Outcomes with Prostate SBRT for Low and Intermediate Risk Prostate Cancer and Comparison to Other Treatment Interventions

Abstract

Treatment of prostate cancer has evolved significantly over the last decade. Active surveillance has been established as the primary treatment for low risk disease. National and international guidelines state that for a patient with low risk localized prostate cancer, brachytherapy (BT), external beam radiotherapy (EBRT) and radical prostatectomy (RP) are appropriate monotherapy options and the outcomes data do not provide a clear-cut evidence for the superiority of any one treatment. Available evidence suggests that there is no difference in clinical progression, incidence of metastases or overall survival between RP or EBRT for low risk patients. Similarly, the paradigm for intermediate risk prostate cancer has shifted with introduction of low-tier and high tier intermediate risk categories. While the low-tier intermediate risk patients are treated with one of many available treatment modalities and difference in clinical outcomes has been shown for those receiving prostatectomy or radiotherapy; high-tier intermediate risk patients, on the other hand have better outcome with combination of EBRT and BT. There is emerging, albeit early evidence that hypofractionated radiotherapy regimens may be appropriate choice in select low-risk and low-tier intermediate risk patients as monotherapy, as well as for select high-tier intermediate risk patients in combination with brachytherapy. In this chapter, we summarize key clinical series and trials to highlight differences in the outcomes among various treatment modalities utilized for treatment of localized prostate cancer and compare those to extreme hypofractionated regimens also known as stereotactic body radiotherapy (SBRT).