Use of ⁶⁸Ga-prostate-specific membrane antigen (PSMA)-11-positron emission tomography (PET)/computed tomography (CT) results in a change in treatment concept for 28% of prostate cancer patients with biochemical recurrence after radical prostatectomy, according to a study published online June 1 in Frontiers in Oncology.
Dirk Bottke, MD, from Xcare Praxis für Strahlentherapie in Trier, Germany, and colleagues examined the impact of ⁶⁸Ga-PSMA-11-PET/CT on the target volume among 76 prostate cancer patients with biochemical recurrence after radical prostatectomy. The patients all had a prostate-specific antigen (PSA) of ≤0.5 ng/mL. An experienced radiation oncologist determined the radiotherapy concept, with and without consideration of the PET/CT.
The researchers found that all 76 patients would have been assigned to RT without considering the PET/CT: 60 to the bed of the prostate and seminal vesicles alone, and 16 also to the pelvic lymph nodes because of histopathologic risk factors. Patients had a median pre-PET/CT PSA level of 0.245 ng/mL. Fifty-four percent of the patients had uptake indicative for tumor recurrence in ⁶⁸Ga-PSMA-11-PET/CT. In 21 patients (28 percent), the results of the PET/CT led to a change in the radiotherapeutic target volume. In 13 patients (17 percent), there were major changes in the target volume, including additional irradiation of lymph nodes or additional or exclusive irradiation of bone metastases. In eight patients (11 percent), minor changes included the additional irradiation of the original seminal vesicle (base) position.
“With 28 percent changes in radiotherapy planning, ⁶⁸Ga-PSMA-11-PET/CT is an important tool in guiding radiation treatment in this patient group,” the authors write. “However, clinical data about the outcome of those treated patients have to be awaited.”