Outcome after PSMA PET/CT based radiotherapy in patients with biochemical persistence or recurrence after radical prostatectomy

Abstract

BackgroundPSMA PET/CT visualises prostate cancer residual disease or recurrence at lower PSA levels compared to conventional imaging and results in a change of treatment in a remarkable high number of patients. Radiotherapy with dose escalation to the former prostate bed has been associated with improved biochemical recurrence-free survival. Thus, it can be hypothesised that PSMA PET/CT-based radiotherapy might improve the prognosis of these patients.MethodsOne hundred twenty-nine patients underwent PSMA PET/CT due to biochemical persistence (52%) or recurrence (48%) after radical prostatectomy without evidence of distant metastases (February 2014–May 2017) and received PSMA PET/CT-based radiotherapy. Biochemical recurrence free survival (PSA ≤ 0.2 ng/ml) was defined as the study endpoint.ResultsPatients with biochemical persistence were significantly more often high-risk patients with significantly shorter time interval before PSMA PET/CT than patients with biochemical recurrence. Patients with biochemical recurrence had significantly more often no evidence of disease or local recurrence only in PSMA PET/CT, whereas patients with biochemical persistence had significantly more often lymph node involvement. Seventy-three patients were started on antiandrogen therapy prior to radiotherapy due to macroscopic disease in PSMA PET/CT. Cumulatively, 70 (66–70.6) Gy was delivered to local macroscopic tumor, 66 (63–66) Gy to the prostate fossa, 61.6 (53.2–66) Gy to PET-positive lymph nodes and 50.4 (45–52.3) Gy to lymphatic pathways. Median PSA after radiotherapy was 0.07 ng/ml with 74% of patients having a PSA ≤ 0.1 ng/ml. After a median follow-up of 20 months, median PSA was 0.07 ng/ml with ongoing antiandrogen therapy in 30 patients. PET-positive patients without antiandrogen therapy at last follow-up (45 patients) had a median PSA of 0.05 ng/ml with 89% of all patients, 94% of patients with biochemical recurrence and 82% of patients with biochemical persistence having a PSA ≤ 0.2 ng/ml. Post-radiotherapy PSA ≤ 0.1 ng/ml and biochemical recurrence vs. persistence were significantly associated with a PSA ≤ 0.2 ng/ml at last follow-up.ConclusionsPSMA PET/CT-based radiotherapy is an effective local salvage treatment option with significant PSA response in patients with biochemical recurrence or persistence after radical prostatectomy leading to deferral of long-term ADT or systemic therapy.

The impact of prostate‐specific antigen persistence after radical prostatectomy on the efficacy of salvage radiotherapy in patients with primary N0 prostate cancer

“…On the other hand, matching for these risk factors reduced the impact of the post-RP PSA level. An association of adverse clinicopathological parameters with the post-RP PSA level has been reported in several recent studies, in one instance even with the PSA threshold at 0.01 ng/mL [8,[15][16][17].…”

Detection Rate and Localization of Prostate Cancer Recurrence Using 68Ga-PSMA-11 PET/MRI in Patients with Low PSA Values ≤ 0.5 ng/mL

“…A change in RT target planning or management was described in 50%-77% of all patients using 68 Ga-PSMA-11 PET/CT (32)(33)(34). In addition, it has been shown that a 68 Ga-PSMA-11 PET/CT-based RT target leads to a significant PSA response in patients with BR (5,6). In our cohort, 68 Ga-PSMA-11 PET/MRIpositive lesions outside a standard RT target volume were found in more than 70% of all patients with PSMA-positive lesions.…”

“…In contrast, a recent metaanalysis demonstrated a detection rate of 45% (95% confidence interval [CI], 39%-52%) using the new 68 Ga-labeled PET tracer targeting the prostate-specific membrane antigen (PSMA) in patients with BR and PSA values of 0.2-0.49 ng/mL (4). PSMA-based targeted radiotherapy (RT) might therefore become an option in patients with BR (5,6). However, data about the oncologic outcome of PSMA-based targeted RT is still limited, and ongoing clinical trials have to be completed before definitive conclusions on the effect of targeted salvage treatments can be drawn (7).…”

Bridging the Imaging Gap: PSMA PET/CT Has a High Impact on Treatment Planning in Prostate Cancer Patients with Biochemical Recurrence—A Narrative Review of the Literature

“…A few studies have already shown the high impact and good response of PSMA-based therapy on outcome (51)(52)(53). However, limitations such as small samples of patients, exclusion of those with metastatic disease, and short-term follow-up might account for nonidentical categories of data.…”