#0837

Targeted Pelvic Lymph Node Dissection with SCOUT for Robotic Prostatectomy

T. Li¹, P. Treacy¹, R. Thanigasalam¹, J. Cotte¹, N. Ahmadi¹, S. Leslie¹

¹Chris O'Brien Lifehouse, Uro-Oncology Department, Sydney, Australia

Introduction:

In prostate cancer, the pelvic lymph nodes are typically the first site of spread. Imaging techniques demonstrate that whilst the internal iliac nodes are usually the initial landing site, this may be an oversimplification upon which standard templates of pelvic lymph node dissection (PLND) are based on. The SCOUT surgical guidance system utilises an infra-red reflector placed under image guidance to localise lesions. There is currently no published literature on its use in targeting lymph nodes in prostate cancer. We present the first ever use of the SCOUT guidance system in targeting and intraoperative identification of suspicious lymph nodes.

Material and methods:

A 62-year-old male was referred with an elevated prostate specific antigen (PSA) level of 5.94 ng/mL. Digital rectal examination found firmness to the right base and mid-gland. MRI of the prostate demonstrated a PI-RADS 4 lesion in the right posterolateral mid-gland in the peripheral zone. It also noted an enlarged left pelvic lymph node located posterior to the external iliac vessels. Biopsy found grade group 2 disease within targeted cores of the right peripheral zone. The patient was referred for a PSMA-PET scan that showed concordant uptake in the right mid-gland laterally with an SUV of 6.4. The enlarged lymph node detected on MRI was found to be avid with an SUV of 4.7, however, no other suspicious sites of metastatic disease were found. A SCOUT reflector was inserted 11 days prior to his operation. It was performed similarly to those inserted for breast lesions, however, a longer coaxial needle was used, and CT guidance was utilised. During PLND, the SCOUT probe was inserted through a 15mm side port (Figure 1). Inside the abdominal cavity, the probe was manipulated with robotic graspers to identify the SCOUT reflector (Figure 2). Live feedback was provided with both audible clicks of increasing frequency and an external console displaying the exact distance between probe and reflector. Once localised, the PLND was carried out, incorporating the reflector in the lymph node packet. When retrieved, the probe confirmed the presence of the reflector in the specimen.

Results:

Histopathology demonstrated grade group 3 acinar adenocarcinoma with cribriform glands. 5 lymph nodes were retrieved, with one lymph node in the SCOUT localised packet. This lymph node demonstrated reactive hyperplasia and nodular hyaline changes but was negative for malignancy. 6- and 12-week post-operative PSA levels remain undetectable.