Abstract P3-03-41: Preoperative wirefree localization of positive axillary lymph nodes 31-365 days prior to surgery: A proposed practical approach to supplement SLN in neoadjuvant therapy patients

Abstract

Abstract The study objective was to evaluate preoperative Wirefree Localization (WFL) placement success rate and device stability 31-365 days prior to successful surgery in patients with node-positive breast cancer prior to neoadjuvant treatment (NAT). Background: Wirefree nonradioactive Localization (WFL) has become a standard of care in over 40,000 breast cancer patients in 300 US sites. The radiologist/surgeon performs preoperative WFL of the positive breast or axillary lymph node (LN) using Mammography (MG), Ultrasound (US) or CT guidance. In August 2018, the FDA expanded clearance of long-term breast WFL to soft tissue and LN. Results of this study further support the ACOSOG-Z1071 subset findings that selected patients with node-positive disease and NAT may be eligible for sentinel lymph node (SLN) surgery and may potentially require less extensive axillary surgery. Long-term (31-365 day) preoperative localization of the biopsy proven positive LN may represent a more practical approach to supplement SLN in NAT patients. Methods: This prospective pilot study enrolled 33 breast cancer patients aged 28-74 (10 Caucasian, 12 African American, 11 Hispanic), with clinical T1-4, N0-2, M0 disease who planned NAT. WFL was performed prior to NAT response and 31 - 365 days preoperatively in the breast and/or positive axillary LN (19 LN only, 4 both breast and LN, 10 breast only). Descriptive statistics were used. Results: This subset analysis showed 23/33 patients were node-positive (10-51 mm size). WFL placements were successful (0-10 mm from center) in all 23/23 patients via US guidance (22 patients, LN 8-35 mm deep to skin) and CT guidance (1 patient, LN 90 mm deep to skin). WFL stability (0 mm migration) throughout NAT was documented on all standard of care (SOC) preoperative surveillance imaging MG, US, MRI, CT and specimen X-rays (0-222 days). Both the target LN and WFL were well visualized on 9/9 MRI and 8/8 PET/CT SOC imaging. WFL successfully supplemented SLN final surgery in 11/23 subjects to date. Conclusions: WFL of positive LN may be successfully performed prior to NAT response, when the lesion is clearly visualized on imaging. Since successful NAT can result in a complete or partial imaging response, a simpler pre-NAT image-guided WFL may replace the more difficult and less reliable localization post-NAT response. The latter can contribute to incomplete removal of the targeted LN, and unintended larger, more disfiguring cancer surgery. This subset analysis provides preliminary information to suggest that up front WFL of positive LN may be performed long-term prior to NAT response with no significant adverse events or device migration. Long-term (31-365 day) preoperative WFL of the biopsy proven positive LN may represent a more practical approach to supplement SLN in NAT patients. If larger scale studies confirm these findings, this may prove a clinically relevant paradigm shift for future LN positive patients to ensure that the targeted LN is successfully removed, potentially requiring fewer and/or less extensive radiology and surgical procedures. ClinicalTrials.gov NCT03015649 accrual: 33/33 Citation Format: Hayes MK, Wright HR, Bloomquist EV. Preoperative wirefree localization of positive axillary lymph nodes 31-365 days prior to surgery: A proposed practical approach to supplement SLN in neoadjuvant therapy patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-03-41.