Abstract
Background and PurposeSalvage radiotherapy (SRT) is the main potentially curative treatment option for prostate cancer patients with post-prostatectomy PSA progression. Improved diagnostics by positron emission tomography/computed tomography (PET/CT) can lead to adjustments in treatment procedures (e.g. target volume of radiotherapy, androgen deprivation therapy). We analyzed the impact of 68Ga-PSMA-11-PET/CT on the target volume in early biochemical recurrence (PSA up to 0.5 ng/ml).Patients and MethodsWe retrospectively analyzed 76 patients with biochemical recurrence after radical prostatectomy in whom SRT was planned after 68Ga-PSMA-11-PET/CT. All patients had a PSA ≤0.5 ng/ml. An experienced radiation oncologist determined the radiotherapy concept, first with consideration of the PET/CT, second hypothetically based on the clinical and pathological features excluding PET/CT results.ResultsWithout considering the PET/CT, all 76 patients would have been assigned to RT, 60 (79%) to the bed of the prostate and seminal vesicles alone, and 16 (21%) also to the pelvic lymph nodes because of histopathologic risk factors. Uptake indicative for tumor recurrence in 68Ga-PSMA-11-PET/CT was found in 54% of the patients. The median pre-PET/CT PSA level was 0.245 ng/ml (range 0.07–0.5 ng/ml). The results of the PET/CT led to a change in the radiotherapeutic target volume in 21 patients (28%). There were major changes in the target volume including the additional irradiation of lymph nodes or the additional or exclusive irradiation of bone metastases in 13 patients (17%). Minor changes including the additional irradiation of original seminal vesicle (base) position resulted in eight patients (11%).ConclusionUsing 68Ga-PSMA-11-PET/CT for radiation planning, a change in the treatment concept was indicated in 28% of patients. With PET/CT, the actual extent of the tumor can be precisely determined even with PSA values of ≤0.5 ng/ml. Thus, the treatment concept can be improved and individualized. This may have a positive impact on progression free survival. Our results warrant further prospective studies.
Highlights
Radical prostatectomy (RP) is considered to be a standard treatment option for patients with clinically localized prostate cancer (PCa)
Pathological tracer uptake as a sign of tumor recurrence in 68Ga-Prostate-specific membrane antigen (PSMA)-11-positron emission tomography/computed tomography (PET/CT) was found in 54% of the patients
In our retrospective study 68Ga-PSMA-11-PET/CT led to changes of the RT target volume in 28% of patients with PSA ≤0.5 ng/ml after RP
Summary
Radical prostatectomy (RP) is considered to be a standard treatment option for patients with clinically localized prostate cancer (PCa). In case of PSA recurrence, salvage radiotherapy (SRT) is the only curative option, resulting in approximately 60% of the patients reachieving an undetectable PSA. The pre-SRT PSA level is a significant factor of progression, with more favorable results for patients with low PSA levels (0.5 ng/ml or less) [3, 4]. Salvage radiotherapy (SRT) is the main potentially curative treatment option for prostate cancer patients with post-prostatectomy PSA progression. Improved diagnostics by positron emission tomography/computed tomography (PET/CT) can lead to adjustments in treatment procedures (e.g. target volume of radiotherapy, androgen deprivation therapy). We analyzed the impact of 68Ga-PSMA-11-PET/CT on the target volume in early biochemical recurrence (PSA up to 0.5 ng/ml)
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