For patients with oligorecurrent prostate cancer following prostatectomy, ⁶⁸Ga-prostate-specific membrane antigen (PSMA)-positron emission tomography (PET)/computed tomography (CT)-directed radiation therapy (PDRT) plus elective RT is associated with improved biochemical-recurrence-free survival (bRFS), according to a study published online May 10 in Frontiers in Oncology.
Simon Kirste, MD, from the University of Freiburg in Germany, and colleagues compared oncological outcomes and toxicity between PDRT and PDRT plus elective RT in a retrospective multicenter study. Data were included from 394 patients with oligorecurrent ⁶⁸Ga-PSMA-PET/CT-positive prostate cancer treated at six academic institutions; bRFS was assessed as the primary end point.
RT was directed only to lesions seen on ⁶⁸Ga-PSMA-PET/CT in 204 patients (51.8 percent), while 48.2 percent received PDRT plus elective RT. The researchers found that three-year bRFS was significantly improved in association with PDRT plus elective RT compared with PDRT alone (53 versus 37 percent); in a multivariable analysis, it remained an independent factor (hazard ratio, 0.29). In the subgroup of patients treated with PDRT and elective prostate bed radiotherapy, the effect was more pronounced, with three-year bRFS of 61 versus 22 percent. After PDRT plus elective RT, acute and late toxicity grade ≥3 was 0.8 and 3 percent, respectively, compared with no toxicity grade ≥3 after PDRT alone.
“⁶⁸Ga-PSMA-PET-directed RT plus elective RT improves bRFS in oligorecurrent prostate cancer patients while slightly increasing side effects,” the authors write. “These findings need to be confirmed in a prospective trial.”