Implementation of molecular imaging with positron emission tomography targeting prostate-specific membrane antigen (PSMA-PET) into modern focal dose-escalation radiotherapy (RT) concepts is feasible for patients with prostate cancer, according to a study published online April 22 in the International Journal of Radiation Oncology, Biology, Physics.
Constantinos Zamboglou, MD, from the University of Freiburg in Germany, and colleagues staged intermediate- and high-risk localized prostate cancer patients with multiparametric magnetic resonance tomography and PSMA-PET and assigned them into two nonrandomized arms to receive treatment with focal dose-escalated moderately hypofractionated RT (arm A) or single-fraction high-dose-rate brachytherapy (HDR-BT) followed by external beam (EB) RT (arm B). Twenty-five patients were enrolled in each of the study arms.
The researchers found that implementation of PET information yielded large median volumes for dose escalation: 10.2 mL and 6.8 mL in arms A and B, respectively. In all patients of arm A, RT dose escalation was feasible, with up to 75 Gy (20 fractions), while dose escalation was feasible in 23 patients in arm B, with up to 19 Gy (one fraction). Between baseline and six-month follow-up, there were no significant differences noted in toxicities, International Prostate Symptom Score, or European Organization for Research and Treatment of Cancer quality of life scores in both arms. At six-month follow-up, there were no grade 3 toxicities reported.
“Implementation of molecular imaging with PSMA-PET to MRI into focal dose-escalated EBRT and HDR-BT was feasible despite a significant increase of boost volumes, and patients maintained a good quality of life due to a low toxicity profile after six months of follow-up,” the authors concluded.
One author disclosed financial ties to the biopharmaceutical industry; the fiducials were provided by Naslund Medical.