Identification of lymphatic pathway involved in the spreading of prostate cancer by fluorescence navigation approach with intraoperatively injected indocyanine green.

OBJECTIVE : The objective of this study was to identify lymphatic vessels draining from the prostate by using a fluorescence navigation (FN) system. METHODS : Fourteen subjects were candidates for radical retropubic prostatectomy (RRP) and pelvic lymph node dissection (PLND). After an indocyanine green solution was injected into the prostate during RRP, lymphatic vessels draining from the prostate were analyzed using a FN system. After PLND based on lymphatic mapping by the FN system (in vivo probing) was performed in the external iliac, obturator and internal iliac regions; the fluorescence of the removed lymph nodes (LNs) was analyzed on the bench (ex vivo probing). RESULTS : Under in vivo and ex vivo probing, the fluorescence intensity of internal iliac nodes was greater than that of external iliac or obturator nodes. CONCLUSION : The current study suggests that using a FN system after injecting indocyanine green is a safe and rational approach for detecting the lymphatic channel draining from the prostate. The major lymphatic pathway involved in the spreading of prostate cancer appears to relate to internal iliac LNs, which would mean that the standard PLND covering external iliac and obturator regions would not keep the cancer from spreading.