Abstract PO2-23-02: Results of a prospective randomised multicentre study comparing indocyanine green (ICG) fluorescence combined with a standard tracer versus ICG alone for sentinel lymph node biopsy in early breast cancer: The INFLUENCE Trial
Authors: Pitsinis Vassilis , Kanitkar Rahul , Vinci Alessio , Elseedawy Emad , Canna Laura , Benson John R 
Published: May 2024

Background:

Use of fluorescence mapping for visualization of lymphatic and nodal tissue for sentinel lymph node biopsy (SNB) reveals high rates of identification (&gt;98%). Studies combining ICG with either blue dye or radioisotope (RI) have shown high levels of concordance (&gt;90%) and comparable performance parameters between ICG and standard tracers for SNB localization. ICG combines many advantages of blue dye and RI without the disadvantages of allergic reactions, staining of skin and surgical tissues along with handling and disposal of radioactivity materials. Moreover, magnetic tracers pose challenges of interference relating to surgical instrumentation and magnetic resonance imaging (MRI). The combination of ICG with a conventional tracer may represent a transition phase and this randomized study evaluates ICG as a sole tracer agent for SNB in early-stage breast cancer.

Methods:

In a prospective randomized study, 100 patients with unilateral clinically node negative tumours scheduled to undergo routine SNB for core-biopsy proven invasive breast cancer (≤5cm) were identified at multidisciplinary meetings [non-invasive tumours excluded]. All patients had pre-operative axillary ultrasound and breast conserving surgery or mastectomy. Patients were recruited in two cohorts (n=50); cohort 1 was assigned to either ICG [2ml 0.5%] alone (n=25) or combined with RI [Technetium99 nanocolloid, 20MBq] (n=25). Cohort 2 received ICG alone (n=25) or combined with blue dye for SNB localization. The number of nodes whether blue, radioactive, fluorescent or a combination thereof were recorded. Lymphatic and nodal tissue was visualized with a fluorescent camera/detection system. Sensitivity of ICG alone and/or in combination with one or another standard tracer was calculated. The main objective was to assess the performance of ICG alone compared with a standard tracer combination in terms of rates of SNB identification along with procedural node positivity rates. Statistical analysis employed Chi-Square test, Fisher’s Exact test, and logistic regression to determine differences between groups.

Results:

A total of 100 patients were randomized between March and December 2022 with 3 patients excluded from analysis (non-receipt of treatment allocation). Amongst evaluable patients (n=97), the overall SNB identification rate was 96.9% and by tracer category as follows: ICG alone = 97.9% (46/47); ICG + RI = 100% (25/25); ICG + blue dye = 92% (23/25). For cohort 1, the procedural node positivity rates were 17% for ICG alone and 18% for ICG + RI with corresponding figures of 12% for ICG alone and 20% for ICG + blue dye for cohort 2. Mean procedural node retrieval per case was 2.5 in ICG alone Vs ICG + Blue Dye and 2.3 in ICG alone Vs ICG/RI cohorts. There were no significant differences (p&gt;0.05) in performance of ICG alone or combined with a standard tracer, with ICG alone being non-inferior in terms of procedural and nodal detection rates. Similar conclusions were reached from a secondary analysis adjusting for BMI, age and mode of detection (screening/symptomatic).

Conclusion:

ICG fluorescence imaging permits real-time visualisation of lymphatics and gives an additional dimension to SNB that appears safe versus the competitive alternatives. These results confirm high sensitivity for fluorescence localisation alone for SNB with comparable performance to combined methods with blue dye or RI. The fluorochrome ICG is reliable as a sole tracer and avoids potential drawbacks of blue dye and RI including staining, allergic reactions, availability and costs.

Citation Format: Vassilis Pitsinis, Rahul Kanitkar, Alessio Vinci, Emad Elseedawy, Laura Canna, John R Benson. Results of a prospective randomised multicentre study comparing indocyanine green (ICG) fluorescence combined with a standard tracer versus ICG alone for sentinel lymph node biopsy in early breast cancer: The INFLUENCE Trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-23-02.