A pilot study to assess near infrared laparoscopy with indocyanine green (ICG) for intraoperative sentinel lymph node mapping in early colon cancer

Abstract

Background

Previous attempts at sentinel lymph node (SLN) mapping in colon cancer have been compromised by ineffective tracers and the inclusion of advanced disease. This study evaluated the feasibility of fluorescence detection of SLNs with indocyanine green (ICG) for lymphatic mapping in T1/T2 clinically staged colonic malignancy.

Methods

Consecutive patients with clinical T1/T2 stage colon cancer underwent endoscopic peritumoral submucosal injection of indocyanine green (ICG) for fluorescence detection of SLN using a near-infrared (NIR) camera. All patients underwent laparoscopic complete mesocolic excision surgery. Detection rate and sensitivity of the NIR-ICG technique were the study endpoints.

Results

Thirty patients mean age = 68 years [range = 38–80], mean BMI = 26.2 (IQR = 24.7–28.6) were studied. Mesocolic sentinel nodes (median = 3/patient) were detected by fluorescence within the standard resection field in 27/30 patients. Overall, ten patients had lymph node metastases, with one of these patients having a failed SLN procedure. Of the 27 patients with completed SLN mapping, nine patients had histologically positive lymph nodes containing malignancy. 3/9 had positive SLNs with 6 false negatives. In five of these false negative patients, tumours were larger than 35 mm with four also being T3/T4.

Conclusion

ICG mapping with NIR fluorescence allowed mesenteric detection of SLNs in clinical T1/T2 stage colonic cancer.

ClinicalTrials.gov

ID: NCT01662752.

Introduction

Current radiological techniques are not sensitive enough to identify the estimated 10–20% of patients with T1 and T2 colon cancer that have nodal involvement [1], [2]. Instead, major surgery is performed in all patients accepting that en bloc mesenteric resection provides no therapeutic benefit for node negative disease. Colectomy exposes patients to a significant risk of morbidity and mortality [3], along with late side effects [4]. Newly developed organ-preserving techniques in the colon are evolving to excise the primary tumour alone [5], [6]. Therefore, there is a need to develop concomitant methods of evaluating the nodal drainage in order to avoid undertreating patients, while allowing those without nodal metastases to be treated by local excision.

The concept of sentinel lymph node mapping (SLNM) in colon cancer is not new, although it has not had the same impact as in breast cancer, melanoma, and gastric cancer [7], [8], [9], [10]. The comparatively poor accuracy shown in previous studies of SLNM in colorectal cancer patients may have been due to the inclusion of patients with locally advanced disease [11], [12], [13], or the use of blue dye, which has limited penetrance through adipose tissue [14], [15], [16], [17]. The near-infrared (NIR) fluorescence tracer indocyanine green (ICG) has been proposed as a more effective mapping agent in colonic malignancy [18], although the study population reported had a comparatively low BMI. NIR-ICG has previously been validated for SLNM in patients with breast cancer [19] and early gastric cancer [8], [9], [10]. The NIR-ICG sentinel mapping technique requires further validation in Western patients with T1/T2 colon cancer.