Abstract
Purpose: Several studies have demonstrated an advantage of 68Ga-PSMA-PET/CT as staging modality for detection of prostate cancer (PCa) metastases. Data concerning metastatic manifestation and impact on PCa development of mesorectal lymph nodes (MLN) is limited. Our investigation describes MLN metastases as index lesion in 68Ga-PSMA PET/CT imaging for recurrent PCa.Methods: Twelve PCa patients with biochemical recurrence (BCR) after primary therapy who prospectively underwent a baseline 68Ga-PSMA-PET/CT initially showed MLN metastases. Eight of these patients received a follow-up 68Ga-PSMA-PET/CT to evaluate treatment response and further evolution. Prostate-specific antigen (PSA)-levels, changes in PSMA-uptake of MLN metastases and further 68Ga-PSMA PET/CT findings were recorded.Results: Median PSA at the first 68Ga-PSMA-PET/CT was 5.39 ng/ml. In all patients therapeutic management changed after the first 68Ga-PSMA-PET/CT. Androgen deprivation therapy (ADT) was initiated in seven of eight patients, one patient restarted initial ADT. Three patients additionally received salvage radiation therapy (sRT) including the prostatic lodge and docetaxel chemotherapy was started in one case. At follow-up, a decrease of PSA-level was detected in all patients (median 2.05 ng/ml) after median 10 months. In six of eight patients we observed a decrease or complete regress of PSMA-uptake in MLN in the follow-up 68Ga-PSMA-PET/CT.Conclusion: MLN metastases detected by 68Ga-PSMA-PET/CT seem to be a relevant localization of tumor manifestation and may serve as index lesion in the treatment of recurrent PCa. Besides the known oncological benefits of ADT and sRT, in case of sole MLN metastases individualized therapy like salvage lymphadenectomy or RT with a defined radiation field could be options for these patients.
Highlights
In Europe the most common cancer in male is prostate cancer (PCa) with growing incidence in the past two decades [1]
Further studies have confirmed the advantage of 68Ga-prostate specific membrane antigen (PSMA) PET/computed tomography (CT) compared to conventional imaging as well as functional 18F-choline-based positron emission tomography/computed tomography (PET/CT) for patients with biochemical recurrence (BCR) [5, 8,9,10,11]
A previous retrospective analysis by Hijazi et al showed PCa metastases in mesorectal lymph nodes (MLN) in 12 of 76 patients with BCR, which were detected by 68Ga-PSMA PET/CT [11]
Summary
In Europe the most common cancer in male is prostate cancer (PCa) with growing incidence in the past two decades [1]. Within 10 years after primary therapy up to 40% of patients develop biochemical recurrence (BCR) [3]. Due to limited sensitivity and specificity conventional imaging methods, such as computed tomography (CT) and magnetic resonance imaging (MRI), might struggle to accurately determine the presence or absence of metastatic or recurrent PCa [4, 5]. Luiting et al demonstrated promising results for detecting PCa relapse by Gallium (68Ga)-labeled PSMA positron emission tomography/computed tomography (PET/CT) (68GaPSMA PET/CT) [7]. Roach et al prospectively investigated the value of 68Ga-PSMA PET/CT in the management of PCa [14]. They found that 68Ga-PSMA PET/CT scans detected previously unsuspected disease and assumed a greater impact in patients with BCR
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