Enhanced pre-operative axillary staging using intradermal microbubbles and contrast-enhanced ultrasound to detect and biopsy sentinel lymph nodes in breast cancer: a potential replacement for axillary surgery

OBJECTIVE: To compare the experience of four UK Centres in the use of intradermal microbubbles and contrast enhanced ultrasound (CEUS) to pre-operatively identify and biopsy sentinel lymph nodes (SLN) in patients with breast cancer. METHODS: In all centres, breast cancer patients had a microbubble/CEUS SLN core biopsy prior to axillary surgery and patients in Centres 1 and 2 had a normal greyscale axillary ultrasound. Data were collected between 2010 and 2016; 1361 from Centre 1 (prospective, sequential), 376 from Centre 2 (retrospective, sequential), 121 from Centre 3 (retrospective, selected) and 48 from Centre 4 (prospective, selected). RESULTS: SLN were successfully core biopsied in 80% (Centre 1), 79.6% (Centre 2), 77.5% (Centre 3) and 88% (Centre 4). The sensitivities to identify all SLN metastases were 46.9% [95% confidence intervals (CI) (39.4-55.1)], 52.5% [95% CI (39.1-65.7)], 46.4% [95% CI (27.5-66.1)] and 45.5% [95% CI (16.7-76.6)], respectively. The specificities were 99.7% [95% CI (I98.9-100)], 98.1% [95% CI (94.5-99.6)], 100% [95% CI (93.2-100%)] and 96.3% [95% CI (81-99.9)], respectively.The negative predictive values were 87.0% [95% CI (84.3-89.3)], 84.5% [95% CI (78.4-89.5)], 86.9% [95% CI (82.4-90.3)] and 86.2% [95% CI (78.4-91.5)], respectively. At Centres 1 and 2, 12/730 (1.6%) and 7/181 (4%), respectively, of patients with a benign microbubble/CEUS SLN core biopsy had two or more lymph node (LN) macrometastases found at the end of primary surgical treatment. CONCLUSION: The identification and biopsy of SLN using CEUS is a reproducible technique. Advances in knowledge: In the era of axillary conservation, microbubble/CEUS SLN core biopsy has the potential to succeed surgical staging of the axilla.