Case Report

⁶⁸Ga-PSMA-PET/CT-Guided Salvage Retroperitoneal Lymph Node Dissection for Disease Relapse After Radical Prostatectomy for Prostate Cancer

La radiothérapie avec modulation d’intensité, puis le guidage par l’image avec marqueurs fiduciels intraprostatiques et la curiethérapie prostatique en monothérapie sont des traitements qui permettent de délivrer une escalade de dose pour des cancers de prostate localisés avec des taux faibles de toxicité aiguë et encore plus faibles de séquelles à long terme. Cette diminution de l’irradiation des tissus sains ainsi que les évolutions technologiques permettent aujourd’hui de proposer des traitements plus courts avec des doses par fraction élevées, de mieux préserver le rectum, d’escalader la dose sur prostate par curiethérapie ou focalement par radiothérapie externe, de mieux cibler les aires ganglionnaires à risque d’être envahies pour des cancers à plus haut risque, de délivrer des irradiations focalisées partielles ou combinées grâce à l’IRM fonctionnelle et la tomographie par émission de positons (TEP) – scanographie. L’innovation en radiothérapie reste étroitement liée à l’innovation imagerie grâce à l’IRM et la TEP-scanographie.

Intensity-modulated radiation therapy, image-guided radiation therapy with fiducial markers and prostate brachytherapy allow the delivery of dose escalation for localized prostate cancer with very low rates of long-term toxicity and sequelae. Nowadays, modern radiotherapy techniques make it possible to shorten treatment time with hypofractionation, to better protect surrounding healthy tissues and to escalate the dose even further. Advances in radiotherapy are closely linked to advances in magnetic resonance imaging (MRI) and/or PET imaging. Functional imaging makes it possible to deliver personalised pelvic nodal radiotherapy, targeting the nodal areas at higher risk of microscopic involvement. In patients with an index lesion at baseline or at failure, MR-based focal therapy or focal dose escalation with brachytherapy or stereotactic body radiation therapy is also currently investigated. MR-based adaptive radiotherapy, which makes it possible to track prostate shifts during radiation delivery, is another step forward in the integration of MR imaging in radiation delivery.

Prostate cancer (PCa) is the most common malignancy in men and a major cause of cancer death. Accurate imaging plays an important role in diagnosis, staging, restaging, detection of biochemical recurrence, and for therapy of patients with PCa. Because no effective treatment is available for advanced PCa, there is an urgent need to develop new and more effective therapeutic strategies. To optimize treatment outcome, especially in high-risk patients with PCa, therapy for PCa is moving rapidly toward personalization. Medical imaging, including positron emission tomography (PET)/computed tomography (CT), plays an important role in personalized medicine in oncology. In the recent years, much focus has been on prostate-specific membrane antigen (PSMA) as a promising target for imaging and therapy with radionuclides, as it is upregulated in most PCa. In the prostate, one potential role for PSMA PET imaging is to help guide focal therapy. Several studies have shown great potential of PSMA PET/CT for initial staging, lymph node staging, and detection of recurrence of PCa, even at very low prostate-specific antigen values after primary therapy. Furthermore, studies have shown that PSMA PET/CT has a higher detection rate than choline PET/CT. Radiolabeled PSMA ligands for therapy show promise in several studies with metastatic PCa and is an area of active investigation. The “image and treat” strategy, with radiolabeled PSMA ligands, has the potential to improve the treatment outcome of patients with PCa and is paving the way for precision medicine in PCa. The aim of this review is to give an overview of recent advancement in PSMA PET and radionuclide therapy for PCa.