Abstract P4-02-02: Low-cost fluorescein guided sentinel lymph node biopsy as an alternative to radio-pharmaceutical guided SLNB -Results of a prospective, comparative validation study

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Abstract Introduction: Sentinel lymph node biopsy (SLNB) is the current standard of care for surgical staging of clinically N0 axilla in breast cancer (BC) patients. The current gold standard technique for SLNB utilizes a radiopharmaceutical (R) and a blue dye (B) in combination (RB). However, in the developing countries, the limited availability and high costs of radiopharmaceutical and gamma probe are major barriers in performing SLNB. Fluorescein (F) is a commonly available, inexpensive and safe lymphophilic dye commonly used for retinal angiography. When injected, it is trapped selectively by lymphatics and rapidly transported to, and concentrated in the lymph nodes, which can be detected as bright fluorescent structures under blue light. Its use can obviate the need for radiopharmaceutical and gamma probe. In this comparative validation study, we used this novel dye and an inexpensive hand-held blue LED light as the method for SLNB, and assessed the SLN identification rate (SLN-IR) & false negative rate (FNR) of SLNB using fluorescein and its combination with blue dye, with those of the gold standard (RB). Methods: After obtaining approval from IEC, in this prospective, comparative validation SLNB study, 40 cN0 early BC patients treated were recruited, starting March 2018. After getting due consent from the patients, SLNB was performed using 99mTc-Sulphur-colloid(and gamma probe), methylene blue & fluorescein (and blue LED light), using the standard injection techniques and timings for R and B. One ml Inj Fluorescein 4%, diluted in 4 ml of saline was injected peri-tumoral and sub-areolar (half and half) just before axillary incision. ALND was performed irrespective of SLNB histology, and the SLN-IR and FNR obtained with various methods compared. Results: All in all, SLNs could be identified in 39 (97.5%) patients using one or the other dye. The SLN-IRs using the investigational dye- fluorescein (F) alone (92.5%), or in combination with methylene blue (FB combination, 92.5%) were identical, and comparable with the gold standard RB combination (SLN-IR 92.5%). However the SLN-IR using radiotracer (R) alone (87.5%), and blue dye alone (72.5%) were significantly inferior compared to the investigational F or FB combination, or the conventional gold standard RB combination. The SLN FNRs were 0% using Radiotracer alone, RB combination, Fluorescein alone and FB combination, while it was 50% using methylene blue dye (B) alone. Conclusions: Results of this novel prospective, comparative validation SLNB study suggest that SLN identification rates and false negative rates using the novel inexpensive fluorescein dye and an LED blue light, used alone or in combination with methylene blue, are comparable to those achieved by using the current gold standard combination of radio-colloid and methylene blue. By replacing the radio-colloid with fluorescein, and gamma probe with LED blue light, we could perform SLNB with similar efficacy and accuracy, but at a fraction of the cost by obviating the use of expensive radio-pharmaceutical and the gamma probe. This low-cost innovation has the potential to be helpful in implementation of cost-effective SLNB across developing world. Citation Format: Gaurav Agarwal, VC Ramya, Sabaretnam Mayilvahanan, Gyan Chand, Anjali Mishra, Amit Agarwal, Saroj K Mishra, Sanjay Gambhir, Vinita Agrawal, Narendra Krishnani, Punita Lal. Low-cost fluorescein guided sentinel lymph node biopsy as an alternative to radio-pharmaceutical guided SLNB -Results of a prospective, comparative validation study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-02-02.