AUTHOR=Leitsmann Conrad , Schmid Marianne , Sahlmann Carsten-Oliver , Trojan Lutz , Strauss Arne 

TITLE=Mesorectal Lymph Node Metastases as Index Lesion in 68Ga-PSMA-PET/CT Imaging for Recurrent Prostate Cancer

JOURNAL=Frontiers in Surgery

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/surgery/articles/10.3389/fsurg.2021.637134

DOI=10.3389/fsurg.2021.637134

ISSN=2296-875X

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 aimed to evaluate 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 showed MLN metastases. Eight of these patients received a follow-up 68Ga-PSMA-PET/CT to evaluate treatment response and further evolution. Development of PSA-values, changes in PSMA-uptake of the 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. Antiandrogen therapy (ADT) was initiated in 7 of 8 patients, one patient restarted initial ADT. Three patients additionally received salvage radiation therapy (sRT) including the prostatic loge and docetaxel chemotherapy was started in one case. At follow-up, a decrease of PSA was detected in all patients (median decrease -2,05 ng/ml) after median 10 months. In 6 of 8 patients we observed a decrease or complete regress of PSMA-uptake in MLN in the follow-up PET/CT. 

Conclusion
MLN metastases detected by 68Ga-PSMA-PET/CT seem to be relevant recurrence localization 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 an individual radiation field could be options for these patients.