Case Report68Ga-PSMA-PET/CT-Guided Salvage Retroperitoneal Lymph Node Dissection for Disease Relapse After Radical Prostatectomy for Prostate Cancer
Introduction
Approximately 30% of patients submitted to radical prostatectomy or radiotherapy for prostate cancer (PCa) will develop local or distant relapse within 10 years from primary therapy, thus receiving a second-line treatment within 5 years.1 The main drawback is the low diagnostic accuracy of conventional imaging techniques (contrast-enhanced computed tomography [CT] and bone scintigraphy) to find the recurrence site at the early phase of beginning biochemical relapse (BR).2, 3 11C-choline and 18F-fluorocyclobutane-1-carboxylic acid (18F-FACBC) positron emission tomography (PET)/computed tomography (CT) may show the site of tumor recurrence earlier than other conventional imaging methods in a single-step examination. The detection rate is directly related to prostate-specific antigen (PSA) values and PSA kinetics.3, 4 Although these procedures have already been demonstrated to have an important clinical impact on patient management,5 their main limitations are lack of sensitivity and suboptimal specificity at low PSA levels.3 Although many results have highlighted the efficacy of salvage lymph node dissection (S-LND) for PCa relapse,6 there is still a lack of PET radiopharmaceuticals that might be considered a valid tool to identify nodal metastases in order to guide future S-LND. Recently, 68Ga-labeled prostate-specific membrane antigen ligand HBED-CC (68Ga-PSMA) PET/CT showed a higher detection rate than 11C-choline-PET/CT,7 with promising results to restage PCa patients during the early phase of BR with low PSA levels.8, 9, 10 We present a case of retroperitoneal S-LND guided by 68Ga-PSMA-PET/CT results in a patient with PSA relapse after radical prostatectomy.
Section snippets
Case Report
A 56-year-old man was diagnosed with clinical T2 PCa with a biopsy Gleason score of 3 + 3 and a preoperative PSA value of 5 ng/mL. The patient underwent laparoscopic extraperitoneal radical prostatectomy in July 2007 by sampling pelvic lymph node (LN) dissection. Final histology revealed a pT3aN1(1/12)Mx PCa, with a Gleason score of 4 + 3. Adjuvant radiotherapy to the prostate bed and antiandrogen (ADT) intermittent therapy was administered. PSA nadir was < 0.2 ng/mL. In May 2013, BR occurred,
Discussion
Among the new imaging techniques used to detect nodal metastases in patients with PCa relapse, 11C-choline-PET/CT is the most used to restage the disease in case of BR. However, 11C-choline-PET/CT shows a lack of sensitivity and suboptimal specificity at low PSA levels.3 This limit is due to the slow proliferation of PCa, which is characterized by a slow membrane metabolism, which causes a small amount of choline uptake. Different radiotracers are currently under evaluation in order to overcome
Conclusion
This case report suggests that 68Ga-PSMA-PET/CT is a promising tool for restaging patients with BR after radical therapy. Furthermore, considering that the preliminary results showed a high accuracy for correctly detecting the site of relapse, in the future, 68Ga-PSMA-PET/CT could be a highly predictive imaging procedure for guiding S-LND.
Disclosure
The authors have stated that they have no conflict of interest.
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