68Ga-PSMA Ligand PET/CT-based Radiotherapy for Lymph Node Relapse of Prostate Cancer After Primary Therapy Delays Initiation of Systemic Therapy

Abstract

Among patients with prostate cancer, tumor relapse after primary therapy particularly occurs in high-risk groups. The standard of care for distant relapse of prostate cancer is androgen-deprivation therapy (ADT), which has a negative impact on the patient's quality of life (1). Recently alternative local treatment strategies have been proposed for patients with oligometastatic disease, who have a better prognosis than patients with extensive disease (2). Local therapies such as radiotherapy could provide effective local control, delay disease progression and therefor reduce the need to initiate systemic therapies (3). The identification of patients with oligometastatic prostate cancer is challenging due to the lack of sufficiently sensitive imaging for detection of low-volume recurrent and metastatic disease in patients with low prostatespecific antigen (PSA) levels (2). In general, positronemission tomography-computed tomography (PET/CT) for radiotherapy has proven helpful in patient selection and target volume delineation, with promising results regarding clinical outcome and toxicity (4, 5). A new diagnostic option in this context is the use of prostate-specific membrane antigen (PSMA) ligands for PET/CT. 68 Ga-PSMA ligand PET/CT has been reported to have a substantially higher diagnostic accuracy for the detection of prostate cancer metastases than choline-based PET/CT, particularly in the case of lymph node metastases (6-10). Data on the effectiveness of 68 Ga-PSMA ligand PET/CT-based radiotherapy for prostate cancer lymph node metastases after primary therapy are limited.The aim of the present study was to assess the clinical outcome and time of initiation of systemic therapies (ADT or chemotherapy) of patients with isolated prostate cancer lymph node metastases after primary therapy treated with 68 Ga-labelled PSMA ligand PET/CT-guided 3D conformal radiotherapy. Patients and MethodsStudy population. Between June 2014 and March 2016, 23 patients with biochemical failure and a PSA above 0.5 ng/ml after primary therapy of prostate cancer underwent 68 Ga-PSMA ligand PET/CT for restaging purposes and were treated with radiotherapy of the 68 Ga-PSMA ligand PET/CT-positive lymph nodes. All cases were discussed 1273

177Lu-PSMA-617 radioligand therapy for a patient with lymph node metastatic prostate cancer

“…The micrometastases were not detected by the PET/CTs. Anyway, an increasing number of studies report that SRT has been guided by 68 Ga-PSMA-HBED-CC PET/CT [ 9 – 12 ].…”

Liquid Biopsy in Oligometastatic Prostate Cancer—A Biologist's Point of View

“…A retrospective study in patients with locally-recurrent and oligometastatic PCa demonstrated that 68 Ga-PSMA ligand and PET/CT-guided RT is strongly associated with slower clinical progression, thus also delaying initiation of systemic treatment. Moreover, the preliminary results in that cohort suggest that RT with 68 Ga-PSMA ligand PET/CT provides local control, with a substantial treatment response (i.e., lower PSA levels) without clinically-relevant side effects (57). Guler et al retrospectively investigated the efficacy and toxicity of 68 Ga-PSMA PET-CT-guided RT for oligometastatic PCa, finding that this technique may be a promising approach to treatment of patients with biochemically-recurrent PCa (58).…”

177Lu-PSMA radioligand therapy of predominant lymph node metastatic prostate cancer

“…The present study selected patients with PC from prospectively recorded databases of consecutive patients treated with LuPRLT at the six centers. The present study followed conventional eligibility criteria for LuPRLT: informed consent to LuPRLT, age > 18 years, histologically proven PC, hemoglobin > 80 g/l, white blood cell counts > 3 × 10 9 cells/l, platelet counts > 75 × 10 9 cells/l, and alanine aminotransferase, aspartate aminotransferase and, with one exception, creatinine < 1.5 × upper limit of normal values [28, 32].…”