The Study: One reason is the standard for including pelvic nodal regions, making radiation volumes much larger. Here’s a comparative analysis of two recently published phase 2 trials on the subject: SATURN and pHART8 (yes, pHART). Each enrolled 30 patients with high-risk disease, and each treated the intact prostate CTV to 8 Gy x 5. As discussed before, SATURN simultaneously treated the seminal vesicles and elective nodes to 5 Gy x 5 and pHART8 the seminal vesicles alone to 6 Gy x 5. At a median follow-up of 4 years for SATURN and 5.5 years for pHART8, there was only one grade 3+ late GI or GU toxicity among all 60 patients: a small bowel obstruction in the setting of multiple previous abdominal surgeries. Most remarkably, 0/30 patients developed biochemical recurrence in SATURN while 6/30 (20%) did in pHART8 including 1 who developed mets.
Bottom Line: SBRT to the prostate and elective nodes deserves eval on more patients with longer follow-up. | Alayed, Int J Radiat Oncol Biol Phys 2019