Login to Access Video or Poster Abstract: MP53-10
Sources of Funding: This research is funded by the Australian Department of Health and Ageing by funding of the Australian Prostate Cancer Research Centre-NSW, and the St Vincent's Prostate Cancer Centre.

Introduction

68Ga-PSMA PET/CT is an emerging imaging modality allowing early detection of metastases in patients with biochemical recurrence (BCR) after primary treatment for prostate cancer. In oligometastatic node-only disease, this raises the question of whether patients may benefit from early salvage treatment of lymph node metastases (LNM). Robot-assisted salvage node dissection (RASND) based on 68Ga-PSMA imaging may represent an option for selected patients with the aim of cure or at least postponing systemic therapies and their inherent quality of life burden.

Methods

Between February 2014 and April 2016, patients who underwent RASND for 68Ga-PSMA-detected oligometastatic node disease across two centres were analysed. Safety and oncological results were reviewed. Definitions of PSA Treatment Response (TR) to RASND were based on primary treatment; success was defined as 6-week PSA<0.2ng/ml (broad) or PSA<0.03ng/mL (strict) in those who had primary prostatectomy, and 6-week PSA < post-RT nadir in those who had primary radiotherapy.

Results

Overall, 35 patients were included in the analysis. A total of 58 lesions were detected on 68Ga-PSMA imaging. Median pre-RASND PSA was 2.2ng/ml (IQR 0.5-5.6) and median time from primary treatment was 61.3 months (IQR 20.5-90.9). 14 patients had targeted dissections, 19 patients unilateral or bilateral extended template dissections and 2 patients a combination of both. In total, 372 lymph nodes were excised. 32 patients (91%) had positive histopathology, with a total of 87 LNM and a median of 2 LNM per patient (IQR 1-3). 8 patients experienced complications, all Clavien Dindo grade ?2. Median follow-up was 12 months (IQR 7.3-18.2). TR was seen in 15 (42.9%) and 11 (31.4%) patients using broad and strict definitions respectively. BCR-free survival (BFS) at a median follow-up of 12 months was 22.9% (broad definition) vs 14.3% (strict definition) for the entire cohort. In those with initial TR, median time to BCR was 3.4 months (IQR 1.8-10.5) and 5.4 months (IQR 1.7-11.8), with broad and strict definitions of initial TR respectively. Clinical progression occurred in 12 patients (34.3%), 2 of which had an initial TR (strict definition).

Conclusions

RASND appears safe and feasible. In our cohort, less than half of patients had a TR to RASND. Given that 68Ga-PSMA imaging may underestimate micro-metastatic disease, long-term cure is unlikely with RASND. Long-term follow-up is required to assess potential QOL and mortality benefits in the subset that achieved BFS at a median follow-up of 8.5 months.

Funding

This research is funded by the Australian Department of Health and Ageing by funding of the Australian Prostate Cancer Research Centre-NSW, and the St Vincent's Prostate Cancer Centre.