Abstract B042: Sentinel lymph node detection in breast cancer: Comparison of blue dye and filtered Technetium 99m sulphur colloid radiotracer injection

Abstract

Abstract Aim: This prospective study was performed to compare the identification rate, sensitivity and specificity of blue dye and filtered Technetium 99m labelled sulphur colloid (Tc99m SC), individually and in combination for the detection of sentinel lymph nodes in clinically node negative early-stage breast cancer. Materials and methods: Thirty-two women with biopsy-proven breast cancer (cT1N0M0-T2N0M0) were included in this prospective study over a period of 18 months (2019-2020). Four peri-areolar intradermal injections of filtered Tc99m SC were administered 2-3 hours before surgery. Sequential dynamic anterior images of the chest were acquired on a gamma camera, followed by anterior and anterior oblique static images and hybrid single photon emission computed tomography / computed tomography (SPECT/CT) of the affected breast and ipsilateral axilla. Pre-operatively, the sites of detected sentinel lymph nodes (SLNs) were marked on the skin surface using a hand-held gamma probe. SLNs were then identified intra-operatively after peri-tumoral methylene blue injection (blue nodes) and with the gamma probe (hot nodes). These SLNs were removed and sent for frozen section histopathology separately, labelled as hot only, blue only and hot and blue. All patients underwent axillary lymph node dissection (ALND). The final histopathology of all lymph nodes excised during ALND and SLN biopsy were analysed. Identification rate, sensitivity and specificity of both the methods for SLN detection individually and in combination were compared. Results: SLN data of 32 female patients aged 54.7±10.6 years with cT1N0M0-T2N0M0 was analysed. In 87.5% of patients (n=28) the same lymph node was identified by blue dye and filtered Tc99m SC and discordance was seen in 12.5% (n=3) patients. No SLN was detected by any method in one patient. Identification rate of filtered Tc99m SC alone, blue dye alone and combination techniques was 96.9% (n=31), 93.8% (n=30) and 96.9% (n=31) respectively. Of total 593 dissected lymph nodes including 78 SLNs (average 2.4±1.7 per patient), metastasis was found in 198 lymph nodes (12/32 patients). The sensitivity and specificity of the procedure considering only filtered Tc99m SC, blue dye alone and combination of the two tracers was found to be 83.3% (95% CI of 51.6-97.9) and 100% (95% CI of 82.4-100), 75% (95% CI of 42.8- 94.5) and 100% (95% CI of 81.5 -100) and 83.3% (95% CI of 51.6-97.9) and 100% (95% CI of 82.4-100) respectively. Conclusion: SLNB with filtered Tc99m SC using the intra operative gamma probe has better identification rate and sensitivity than blue dye in detecting SLN, while preoperative SPECT/CT helped the surgeon to locate the SLN during surgery. Blue dye has a complementary role in identifying the SLN due to ease of visualisation while operating. Citation Format: Anish Bhattacharya, Yamini Mathur, Ishita Laroiya, Amanjeet Bal, Sarika Sharma, Bhagwant R. Mittal. Sentinel lymph node detection in breast cancer: Comparison of blue dye and filtered Technetium 99m sulphur colloid radiotracer injection [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B042.