Salvage ablative radiation is one treatment option on the table for local recurrence following initial definitive prostate radiation. Here is a dosimetric analysis of 141 plans and linked outcomes following a common prostate re-irradiation regimen of 36 Gy in 6 fractions across two French centers. A priori dosimetric goals included planning target volume V95% ≥ 95%, rectum V12Gy < 20% and V27 Gy < 2cc, and bladder V12Gy < 15% and V27Gy < 5 cc. Unfortunately, only 1 in 5 plans met all the above constraints and virtually none if the clinical target volume was ≥ half the prostate volume. As expected, dosimetry was worse with increasing target volumes. Based on patient toxicity data, the authors suggest the slightly looser alternative constraints of rectum V12 Gy< 25% and bladder V12 Gy< 25% when treating larger targets. | Baty, Pract Radiat Oncol 2023
