Impact of indocyanine green-guided extended pelvic lymph node dissection during robot-assisted radical prostatectomy

To evaluate the effectiveness of indocyanine green-guided extended pelvic lymph node dissection during robot-assisted radical prostatectomy for intermediate- to high-risk prostate cancer.

After institutional review board approval, between July 2017 and December 2018, we carried out 100 indocyanine green-guided extended pelvic lymph node dissections in patients with localized intermediate- and high-risk prostate cancer, using the Firefly (Novadaq Technologies, Mississauga, ON, Canada) and da Vinci Xi surgical system (Intuitive Surgical, Sunnyvale, CA, USA). Indocyanine green was injected transrectally using ultrasound sonography before each surgery. Then, lymphatic drainage patterns and pathological findings were recorded.

Lymphatic drainage routes were successfully determined in 91 right-sided and 90 left-sided cases. Five main lymphatic pathways and sites were identified: (i) an internal route (57%); (ii) a lateral route (50%); (iii) a presacral route (20%); (iv) a paravesical artery site (20%); and (v) a pre-prostatic site (5%). Lymph node metastasis was positive in 15 patients, with 44 pathologically confirmed metastatic lymph nodes. Metastatic fluorescent lymph nodes were found in 15 out of 44 lymph nodes (34.1%). For sentinel lymph node identification, the 34% sensitivity and 64.8% specificity rates were detected in regard to identification of lymph node metastasis.

Lymphatic drainage patterns from the prostate can be identified and classified using indocyanine green-guided extended pelvic lymph node dissections. Although the direct role of fluorescent lymph nodes in sentinel lymph node identification appears to be limited, the identification of lymphatic pathways could contribute to high-quality extended pelvic lymph node dissection during robot-assisted radical prostatectomy.