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. Objectif : L’objectif de l’etude etait de reperer les vaisseaux lymphatiques quittant la prostate a l’aide d’un systeme d’imagerie par fluorescence (IF). Methodologie : Quatorze sujets devaient subir une prostatectomie radicale retropubienne (PRR) et une lymphadenectomie pelvienne. Apres injection d’une solution de vert d’indocyanine dans la prostate pendant la PRR, les vaisseaux lymphatiques drainant la prostate ont ete analyses par IF. Une lymphadenectomie pelvienne fondee sur la cartographie lymphatique par IF (exploration in vivo) a ensuite ete realisee dans les regions de la fosse iliaque externe, de l’obturateur et de la fosse iliaque interne; la fluorescence des ganglions lymphatiques retires a ete analysee sans delai (exploration ex vivo). Resultats : Lors de l’exploration in vivo et ex vivo, l’intensite de la fluorescence des ganglions iliaques internes etait plus forte que celle des ganglions iliaques externes ou des ganglions obturateurs. Conclusion : Cette etude porte a croire que l’IF apres injection de vert d’indocyanine est une methode sure et rationnelle pour reperer les vaisseaux lymphatiques drainant la prostate. La principale voie lymphatique de propagation du cancer de la prostate semble etre reliee aux ganglions lymphatiques iliaques internes, ce qui signifie que la lymphadenectomie pelvienne standard retirant les ganglions iliaques externes et obturateurs n’empecherait pas le cancer de se propager.