How to cite: Stock RG. “SBRT and Brachytherapy.” Grand Rounds in Urology. October 23, 2025. Accessed Apr 2026. https://grandroundsinurology.com/sbrt-and-brachytherapy/
Summary
Richard G. Stock, MD, Professor of Radiation Oncology, Mount Sinai, New York, New York, reviews the rationale, evidence base, and early outcomes of combining stereotactic body radiation therapy (SBRT) with brachytherapy in intermediate- and high-risk prostate cancer. Dr. Stock centers on biologic effective dose (BED) as a key determinant of durable disease control, explaining why combining modalities with different dose-rate characteristics may improve tumor cell kill while maintaining acceptable toxicity.
He begins with a historical review of combination therapy using external beam radiation plus low-dose-rate seed implants. Long-term series are discussed, showing durable biochemical relapse-free survival with follow-up extending beyond a decade, including in higher-risk patients. Dr. Stock highlights that these outcomes remain strong across prostate-specific antigen (PSA) strata and Gleason categories, while acknowledging that the highest-grade disease still carries substantial risk of distant failure.
Multi-institutional outcome data are then reviewed, with higher BED categories associated with improved biochemical freedom from failure. In these datasets, the best-performing dose groups are closely associated with combined approaches, most commonly brachytherapy plus external beam radiation. Randomized evidence from ASCENDE-RT supports the notion that a brachytherapy boost improves biochemical control compared with an external beam boost alone in higher-tier intermediate- and high-risk populations.
Dr. Stock shifts to SBRT, summarizing randomized trials that established ultrahypofractionated radiation as comparable to conventional or moderately hypofractionated external beam radiation in terms of cancer control and toxicity. He emphasizes SBRT’s practical advantage of shortening treatment time.
Early-phase experiences combining SBRT with brachytherapy are presented, including low- and high-dose-rate approaches. These studies show expected short-term urinary symptom flares with later improvement, favorable PSA declines, and low early biochemical failure rates.
Dr. Stock also provides an update on Mount Sinai’s experience combining palladium-103 brachytherapy with SBRT and notes the increasing role of prostate-specific membrane antigen positron emission tomography (PSMA PET) in confirming eligibility by excluding extra-prostatic spread.
About the 28th Annual Southwest Prostate Cancer Symposium:
Presented by Program Chairs Nelson N. Stone, MD, Richard G. Stock, MD, and William K. Oh, MD, this conference educated attendees about advances in the management of localized and advanced prostate cancer, with a focus on imaging, technology, and training in the related devices. It included a scientific session, as well as live demonstrations of surgical techniques. You can learn more about the conference here.
ABOUT THE AUTHOR
Richard G. Stock, MD, is a Professor of Radiation Oncology at Mount Sinai in New York, New York. Dr. Stock’s clinical interests include cancers of the bladder, prostate, testis, and bone. His research focuses on prostate cancer and prostate brachytherapy. Dr. Stock is best known for establishing a comprehensive prostate cancer database with a corresponding IRB approved protocol to track treatment outcomes following prostate cancer therapies.
