The use of fluorescence imaging with indocyanine green (ICG) for sentinel lymph node detection during robot-assisted radical prostatectomy

Background. Prostate cancer is the most common malignant neoplasm among men and the second leading cause of cancer-related mortality. According to studies, lymph node metastases are detected in approximately 15 % of patients after radical prostatectomy combined with extended pelvic lymph node dissection. In line with the European Association of Urology guidelines, extended pelvic lymph node dissection should be performed in high-risk prostate cancer cases and in intermediate-risk patients where validated nomograms predict a significant likelihood of lymph node involvement.

Modern surgical practice emphasizes the development of high-precision intraoperative imaging techniques to enhance the efficacy of interventions. One such innovative method is near-infrared fluorescence imaging, which utilizes fluorophores – substances that emit light upon laser excitation. For example, indocyanine green (ICG) is used as a contrast agent for fluorescence-guided surgery, improving tissue structure identification and surgical precision.

Aim. To evaluate the feasibility of fluorescence diagnostics using ICG during robot-assisted radical prostatectomy with extended pelvic lymph node dissection.

Materials and methods. At the A. I. Evdokimov Moscow State University of Medicine and Dentistry’s Urology Clinic (based at the S. I. Spasokukotsky City Clinical Hospital, Moscow Healthcare Department), 12 patients diagnosed with prostate cancer were analyzed between 2022 and 2023. Inclusion criteria were localized prostate cancer with histologically confirmed adenocarcinoma (Gleason score ≥7 (3 + 4)) and preoperative risk of lymph node metastasis exceeding 5 % as per the A. Briganti et al. (2012) nomogram. All patients underwent robot-assisted radical prostatectomy and pelvic lymph node dissection. During surgery, intraprostatic injection of ICG solution was performed after prostate isolation, followed by fluorescence imaging of lymph nodes using the FireFly™ mode on the DaVinci Xi™ robotic system.

Results. Patients were divided into two groups: Group 1 (n = 6) included patients with MRI-suspected pelvic lymph node metastases, and Group 2 (n = 6) had no imaging abnormalities. Postoperative histology revealed lymph node metastases in 5/6 patients in Group 1. In one patient from Group 1, metastatic involvement was confined to a single sentinel lymph node, which was visualized using ICG. No metastases were detected in Group 2. The mean fluorescence visualization time for pelvic lymph nodes was 17 minutes. Sentinel lymph nodes were identified in 6/12 patients, with intraoperative frozen section analysis confirming metastatic spread into these nodes.

Conclusion. Intraoperative fluorescence diagnostics with ICG is a safe and practical method to improve surgical outcomes in prostate cancer treatment. ICG enhances the identification of key anatomical landmarks and pathological structures. Sentinel lymph node biopsy may reduce complications associated with extended pelvic lymph node dissection and improve staging by enabling targeted removal of metastatic lymph nodes beyond the standard pelvic lymph node dissection template.