Sentinel lymph node detection in early ovarian cancer: the role of indocyanine green as a single tracer.

Objective: This study aimed to evaluate the usefulness of indocyanine green (ICG) as a single tracer for sentinel lymph node (SLN) biopsy in apparent early-stage ovarian cancer and analyze the role of ultra-staging for metastasis detection.

Methods: A retrospective, observational study was performed including patients with confirmed early-stage ovarian cancer. A total of 0.2 to 0.5 mL of ICG (1.25 mg/mL) was injected at the utero-ovarian ligament stump versus the cervix for pelvic SLN detection and at the infundibulopelvic ligament stump for para-aortic SLN detection, followed by systematic surgical staging. SLNs and non-SLNs were processed with a standard protocol, and then ultra-staging analysis was performed for the SLNs. The primary outcomes included detection rate and diagnostic accuracy (sensitivity and negative predictive value) of ICG for SLN's detection in pelvic and para-aortic fields. The secondary outcome was to determine the detection rate of SLN ultra-staging for metastasis detection.

Results: A total of 31 patients were included. The intra-operative SLN detection rates were 72% (95% CI 54.4% to 89.6%) for the pelvic field and 87.1% (95% CI 75.3% to 98.9%) for the para-aortic field. However, empty packets reduced the true detection rates to 52% (95% CI 32.4% to 71.6%) and 81% (95% CI 66.7% to 94.6%), respectively. For pelvic SLN, the negative predictive value was 100% (95% CI 82.4% to 100%), whereas the diagnostic accuracy and sensitivity could not be calculated because of the absence of metastasis. For para-aortic SLN, the diagnostic accuracy, sensitivity, and negative predictive value were 96.3% (95% CI 88% to 100%), 50% (95% CI 9.5% to 90.5%), and 96.2% (95% CI 81.1% to 99.3%), respectively. The only patient with a positive SLN (3.3%) was detected by micro-metastasis thanks to ultra-staging analysis (100%).

Conclusions: The low volume of ICG (range; 0.2-0.5 mL) as a single tracer for SLN mapping in early-stage ovarian cancer shows a high negative predictive value but limited sensitivity and lead to empty packets detection. Ultra-staging allows low-volume metastasis detection, but its prognostic significance requires further evaluation.