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

Abstract

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. RésuméObjectif : L'objectif de l'étude était de repérer les vaisseaux lymphatiques quittant la prostate à l'aide d'un système d'imagerie par fluorescence (IF). Méthodologie : Quatorze sujets devaient subir une prostatectomie radicale rétropubienne (PRR) et une lymphadénectomie pelvienne. Après injection d'une solution de vert d'indocyanine dans la prostate pendant la PRR, les vaisseaux lymphatiques drainant la prostate ont été analysés par IF. Une lymphadénectomie pelvienne fondée sur la cartographie lymphatique par IF (exploration in vivo) a ensuite été réalisée dans les régions de la fosse iliaque externe, de l'obturateur et de la fosse iliaque interne; la fluorescence des ganglions lymphatiques retirés a été analysée sans délai (exploration ex vivo). Résultats : Lors de l'exploration in vivo et ex vivo, l'intensité de la fluorescence des ganglions iliaques internes était plus forte que celle des ganglions iliaques externes ou des ganglions obturateurs. Conclusion : Cette étude porte à croire que l'IF après injection de vert d'indocyanine est une méthode sûre et rationnelle pour repérer les vaisseaux lymphatiques drainant la prostate. La principale voie lymphatique de propagation du cancer de la prostate semble être reliée aux ganglions lymphatiques iliaques internes, ce qui signifie que la lymphadénectomie pelvienne standard retirant les ganglions iliaques externes et obturateurs n'empêcherait pas le cancer de se propager.

A Review of Indocyanine Green Fluorescent Imaging in Surgery

“…Following the clinical approval of ICG for cutaneous Kaposi's sarcoma and cutaneous metastases of a rectal carcinoma they have been treated successfully [157–159]. Crane et al have very recently used ICG in transcutaneous SLN detection in vulvar cancer patients [160] and Inoue et al for identification of lymphatic pathway involved in the spreading of prostate cancer [161]. …”

Advances in sentinel node dissection in prostate cancer from a technical perspective

“…The detection rate of the SN procedure ranged 76-100%. 5,8,9,12,23,25,29,31,33,36,[43][44][45][46][47][48] A total of 13-75% of the patients showed one or more SN outside the limited PLND template. In addition, SN were detected outside the standard PLND in 51.8-76.9% of the patients with positive LN.…”

“…In 4.1-25% of patients, SN outside the ePLND template were found, whereas 3.5-17% of patients with positive LN had SN metastases outside the ePLND template. 5,7,8,[23][24][25]27,28,31,33,37,[43][44][45]47,[49][50][51][52][53][54] In these studies, the median percentage of positive LN was 20.4% (range 4.7-50) with a FN rate of 1% (range 0-20), respectively.…”

“…43 Using a fluorescence laparoscope (Karl Storz GmbH & Co. KG), van der Poel et al extended the approach into the laparoscopic setting. In their initial feasibility study, they showed that fluorescence imaging, next to preoperative SN mapping, could help to optimize intraoperative SN localization.…”