Building on the landmark FLAME trial, the new ESTRO consensus recommendations provide a practical roadmap for implementing focal boosting in localized prostate cancer, reinforcing level I evidence that advanced image-guided focal dose-escalation improves biochemical progression-free survival without increasing side effects when organ-at-risk constraints are prioritized. Ideal candidates are primarily unfavorable intermediate- and high-risk patients with clearly visible intraprostatic lesions on mpMRI and/or PSMA PET. For conventional 35-fraction regimens, the panel recommends 77 Gy to the prostate with isotolerated (i.e., constraints-permitting) boosting up to 95 Gy; for 20-fraction regimens, 60 Gy to the prostate with at least a 67 Gy focal boost is favored. Simultaneous integrated boost (SIB) is preferred over sequential boosting, and organ-at-risk constraints always trump target coverage: This means decreasing boost prescription as needed to limit urethra D0.1 cc ≤ 80 Gy and rectum D1 cc < 77 Gy over 35 fractions. Constraints for popular hypofractionated 20- or 28-fraction courses are less established and, while no less important, require some extrapolation. Finally, while ultra-hypofractionated boost strategies remain promising, the panel stops short of endorsing them as routine standard of care outside ongoing trials. | Willigenburg, Radiother Oncol 2026
