Top Line: The perfect balance of safety and efficacy when employing reirradiation for locally-recurrent prostate cancer is an area of ongoing debate.
The Study: On this phase 1 trial! eight patients with biopsy-proven intra-prostatic recurrence following upfront definitive radiation received focal salvage ablative radiation without androgen deprivation therapy (ADT). Importantly all enrollees had intraprostatic recurrence only as supported by re-staging PSMA-PET and multiparametric MRI of the pelvis. The gross tumor volume (GTV) was defined using the above imaging and the planning target volume (PTV) was a radial 0.5 cm expansion with the exception of 0.3 cm posterior and superior. The plan was to deliver 5 total fractions given every other day to escalating total doses of 40 → 42.5 → 45 Gy with three patients treated at each level. However, the first two patients treated to 42.5 Gy experienced dose-limiting events defined as grade 3+ GU or GI toxicity. Therefore, three additional patients were treated to 40 Gy (six total), the deemed max tolerated dose. At a median follow-up of 35 months, one patient had experienced a subsequent biochemical failure at 33 months. There were three grade 2 GU events and one G2 GI event, ironically the latter occurring after rectal wall infiltration of a hydrogel spacer. | Patel, Pract Radiat Oncol 2023
The Study: On this phase 1 trial! eight patients with biopsy-proven intra-prostatic recurrence following upfront definitive radiation received focal salvage ablative radiation without androgen deprivation therapy (ADT). Importantly all enrollees had intraprostatic recurrence only as supported by re-staging PSMA-PET and multiparametric MRI of the pelvis. The gross tumor volume (GTV) was defined using the above imaging and the planning target volume (PTV) was a radial 0.5 cm expansion with the exception of 0.3 cm posterior and superior. The plan was to deliver 5 total fractions given every other day to escalating total doses of 40 → 42.5 → 45 Gy with three patients treated at each level. However, the first two patients treated to 42.5 Gy experienced dose-limiting events defined as grade 3+ GU or GI toxicity. Therefore, three additional patients were treated to 40 Gy (six total), the deemed max tolerated dose. At a median follow-up of 35 months, one patient had experienced a subsequent biochemical failure at 33 months. There were three grade 2 GU events and one G2 GI event, ironically the latter occurring after rectal wall infiltration of a hydrogel spacer. | Patel, Pract Radiat Oncol 2023