A comparison of colorimetric versus fluorometric sentinel lymph node mapping during robotic surgery for endometrial cancer

Objective: The study objective was to compare the ability to detect sentinel lymph nodes (SLNs) in women with endometrial cancer (EC) or complex atypical hyperplasia (CAH) using fluorometric imaging with indocyanine green (ICG) versus colorimetric imaging with isosulfan blue (ISB).

Methods: Women underwent SLN mapping, with either ISB or ICG, during robotic-assisted total laparoscopic hysterectomy (RA-TLH) from September 2012 to March 2014. SLNs were submitted for permanent pathologic analysis. Completion lymphadenectomy and ultrastaging were performed according to institutional protocols.

Results: RA-TLH and SLN mapping was performed in 71 women; 64 had EC (64) and 7 had CAH. Age, body mass index (BMI), stage and tumor characteristics were similar in the ICG versus the ISB cohorts. Overall, SLNs were identified bilaterally (62.0%), unilaterally (21.1%), or neither (16.9%), and in 103 of 142 hemi-pelvises (72.5%). The mean number of SLNs retrieved per hemipelvis was 2.23(SD 1.7). SLNs were identified in the hypogastric (76.8%), external iliac (14.2%), common iliac (4.5%) and paraaortic (4.5%) regions. ICG mapped bilaterally in 78.9% of women compared with 42.4% of those injected with ISB (p=0.02). Five women (7%) had positive lymph nodes, all identified by the SLN protocol (false negative rate: 0%). On multivariate analysis, BMI was negatively correlated with bilateral mapping success (p=0.02). When stratified by dye type, the association with BMI was only significant for ISB (p=0.03).

Conclusions: Fluorescence imaging with ICG may be superior to colorimetric imaging with ISB in women undergoing SLN mapping for endometrial cancer. SLN mapping success is negatively associated with increasing patient BMI only when ISB is used.