Top Line: If a clinically node-positive axilla converts to negative after neoadjuvant therapy for node-positive breast cancer, should sentinel node sampling (SNS) or a full axillary dissection be performed.
The Study: The theoretical downside of SNS is aberrant nodal drainage subsequent to gross pathologic disease that is now shrunken and scarred. Most data on the subject reports a false negative rate of at least 12%, and this can be much greater when only one node is sampled. Another technique to consider in this setting is lower axillary sampling (LAS), which consists of en bloc resection of fat and nodes just below the first intercostobrachial nerve. LAS is particularly popular in lower-resource settings because no nuclear medicine is required. In yet another pragmatic study out of Tata Memorial, 730 women post-neoadjuvant chemo had SNS (using dual tracers), LAS, and finally completion axillary dissection to compare their efficacies at ruling out nodal disease. Over ⅓ (38.6%) of patients had residual nodal disease after full dissection. In all but one case, the sentinel node was located within the LAS specimen. Most importantly, the false negative rate of SNS was 20% (18% even with 3+ sentinel nodes sampled) compared to 10% for LAS. Now, a couple of notes. First, this study was performed prior to data indicating initial clipping of clinically positive nodes can lower the false negative rate of SNS. Second, toxicity cannot be compared, of course, since every woman received completion axillary dissection.
TBL: The much more accessible lower axillary sampling technique appears more reliable than sentinel node sampling (without a clip) at ruling out axillary nodal disease following neoadjuvant chemo for breast cancer. | Parmar, JCO Glob Oncol 2020