What is the comparison between Whole Pelvic Radiation Therapy (WPRT) and Stereotactic Body Radiation Therapy (SBRT) for oligometastatic prostate cancer?

From the Guidelines

Whole Pelvic Radiation Therapy (WPRT) and Stereotactic Body Radiation Therapy (SBRT) for oligometastatic prostate cancer are not directly compared in the provided evidence. However, based on the available data, SBRT appears to be a viable option for treating oligometastatic disease, with high local control rates and minimal toxicity 1.

Key Points

• SBRT is a treatment that is accurate and precise, with a high dose of radiation (typically 6–18 Gy) in fewer treatment sessions, achieving a high biological effectiveness while sparing surrounding tissues 1.
• Local control rates with SBRT are high, ranging from 92% to 97% in various studies 1.
• Toxicity associated with SBRT is minimal, with grade 3-4 events reported in 13% to 26% of patients 1.
• Oligometastatic disease can be effectively treated with SBRT, with some studies showing durable progression-free survival (PFS) and overall survival (OS) rates 1.
• WPRT is not directly compared to SBRT in the provided evidence, but it is a common treatment approach for prostate cancer.

Treatment Considerations

• Patient selection is crucial when considering SBRT for oligometastatic disease, with factors such as tumor location, size, and number of metastases influencing treatment decisions 1.
• Combination therapy with immunotherapy and SBRT may be safe, but its efficacy is still being investigated, with some studies showing no significant benefit 1.
• Clinical trials are ongoing to evaluate the efficacy and safety of SBRT in various cancer types, including prostate cancer.

From the Research

Comparison of Whole Pelvic Radiation Therapy (WPRT) and Stereotactic Body Radiation Therapy (SBRT) for Oligometastatic Prostate Cancer

• The efficacy of SBRT in oligometastatic prostate cancer has been evaluated in several studies, with local control rates ranging from 84% to 100% at 6-24 months 2, 3, 4.
• WPRT with SBRT boost has been shown to be effective in patients with high-risk prostate cancer, with similar biochemical-free and overall survival rates compared to conventionally fractionated radiotherapy (CFRT) 5.
• A prospective study of SBRT with concomitant WPRT for high-risk localized prostate cancer patients using 1.5 Tesla magnetic resonance guidance reported favorable treatment-related toxicities and encouraging patient-reported quality of life 6.
• The comparison between WPRT and SBRT for oligometastatic prostate cancer is limited, but available data suggest that SBRT may be a safe and effective modality for treating oligometastatic prostate cancer, with the potential to defer palliative androgen deprivation therapy 3.
• Further prospective trials are necessary to better define the selection of patients and to evaluate the combination of SBRT and new systemic drugs in castration-resistant patients 2, 4.

Toxicity Profiles

• SBRT has been shown to have a low toxicity profile, with grade 1 and 2 toxicities around 10% and no grade 3 side effects reported in some studies 3, 4.
• WPRT with SBRT boost has been associated with minimal toxicity, with no acute grade 3 or higher gastrointestinal (GI) and genitourinary (GU) toxicity reported 5.
• The prospective study of SBRT with concomitant WPRT reported maximum cumulative acute GI/GU grade 1 and 2 toxicity rates of 19.0% and 81.0%, respectively, with no grade 3 toxicities reported 6.

Clinical Outcomes

• The clinical outcomes of SBRT for oligometastatic prostate cancer have been reported in several studies, with median progression-free survival (PFS) ranging from 6.6 to 24 months 2, 3.
• WPRT with SBRT boost has been associated with similar biochemical-free and overall survival rates compared to CFRT, with estimated 4-year overall survival rates of 97.7% and 91.6%, respectively 5.
• The prospective study of SBRT with concomitant WPRT reported early post-MRgSBRT biochemical responses, with biochemical recurrence occurring in one patient at month 18 6.