A lymph node containing metastatic disease is marked with a clip prior to pre-operative (neoadjuvant) chemotherapy so that it can be identified and removed during future surgery. Targeted Axillary Dissection (TAD) refers to the removal of this lymph node with a clip at the time of sentinel lymph node (SLN) surgery for axillary staging. TAD improves the accuracy of the surgical procedure over SLN surgery alone.
Improved Axillary Evaluation Following Neoadjuvant Therapy for Patients with Node-Positive Breast Cancer Using Selective Evaluation of Clipped Nodes: Implementation of Targeted Axillary Dissection
Authors: Caudle AS, Yang WT, Krishnamurthy S, et al.
Source: J Clin Oncol. 2016 Jan 25. [Epub ahead of print]. PMID: 26811528
The presence of disease in the lymph nodes in patients with breast cancer is associated with decreased survival and influences recommendations regarding additional therapies including radiation and chemotherapy. When disease is present in the lymph nodes at the time of initial diagnosis with breast cancer, patients often receive chemotherapy upfront (prior to surgery). After chemotherapy, the disease in the lymph nodes is eradicated in 40-75% of patients. Sentinel lymph node (SLN) surgery is a well-accepted staging procedure performed at the time of surgery both in patients who have surgery first (did not receive chemotherapy upfront) and patients that have clinically negative lymph nodes treated with upfront chemotherapy followed by surgery. Until recently, SLN surgery after chemotherapy was not routinely used in patients who presented with node positive disease and were treated with chemotherapy upfront. Several recent trials have looked at the false negative rate (FNR) of SLN surgery in this setting. As a result, increasingly SLN surgery is being performed after chemotherapy in patients presenting with node positive disease. The studies identified several ways to improve the accuracy of the SLN surgery in this setting. One way to improve accuracy of the procedure, seen in a subgroup analysis of the ACOSOG Z1071 trial, was to have a clip placed in the positive lymph node at the time of the initial diagnosis of lymph node involvement and then to make sure that this clipped lymph node is removed at the time of SLN surgery after chemotherapy.
The authors of this study (Caudle, et al.) coined a new procedure name called targeted axillary dissection (TAD), which ensures resection of the clipped lymph node at the time of SLN surgery. The authors kept a registry of all patients at MD Anderson Cancer Center from 2011-2015 who had biopsy-confirmed breast cancer with axillary nodal disease. The lymph node positive for cancer was marked with a clip prior to chemotherapy, so it could be identified at time of surgery after chemotherapy was completed. During surgery, they performed standard SLN surgery and localized excision of the clipped node together, known as targeted axillary dissection (TAD). They also performed a complete ALND so they could examine how accurate TAD is. In this series of 120 patients, they showed that removal of the clipped node alone had a false negative rate (FNR) — where the clipped node did not have cancer but the remaining lymph nodes did — of 4.2% (5 of 120 patients), which is better than the FNR for SLN surgery alone of 10.1% (7 of 69 patients). TAD (SLN surgery + removal of the clipped node) led to an even lower FNR of 1.4% (1 of 74 patients). This improvement is accounted for because in 23% of the cases (31 of 134), the clipped node was not one of the sentinel lymph nodes.
In summary, targeted axillary dissection (TAD) improves the accuracy of sentinel lymph node surgery after chemotherapy by the addition of removing a clipped lymph node that was known to contain cancer prior to chemotherapy. While this approach is new and has not been widely studied across multiple institutions, it provides a way to further improve the accuracy of SLN surgery in this setting and allow patients with eradiation of lymph node disease to avoid complete axillary lymph node dissection (ALND), sparing them its potential complications. Patients with no remaining disease in the lymph nodes after chemotherapy can potentially avoid ALND and may also be candidates for the NSABP B-51 clinical trial. Patients who do have remaining disease in the axillary nodes may be candidates for Alliance A11202 clinical trial comparing ALND to axillary radiation in this setting.