hypo-FLAME was a single arm phase 2 study investigating focal boost to intraprostatic disease using SBRT. It included 100 patients with intermediate and high risk (75%) prostate cancer with a visible target on MRI. The CTV consisted of the prostate and the MRI-defined GTV plus a 4 mm margin (but excluding OARs) to account for possible ECE. The seminal vesicles were included at physician discretion. An additional 4 mm PTV margin was used. The rectum and urethra also had a 2 mm PRV margin. The PTV received 33.25 Gy in 5 fractions, the prostate received 35 Gy, and the GTV received up to 50 Gy while still meeting OAR constraints. Those included rectum D0.03cc < 40 Gy, rectum PRV D0.03 cc < 42 Gy, rectum D2cc < 35 Gy. The urethra PRV was limited to a D0.03cc <42 Gy. The median near-minimum dose to the GTV was just over 40 Gy and mean dose was 45 Gy. Most (62%) received ADT. At 5 years, the rate of biochemical disease free survival was 93%. The rates of grade 2+ GI and GU toxicity were 12% and 4%, respectively. | Draulans, Radiother Oncol 2024
