Ultrasound with Fine-Needle Aspiration Cytology Before Lumpectomy Can Spare Some Women Sentinel Lymph Node Biopsy
OCTOBER 09, 2009
In 30% of women with early stage breast cancer who were scheduled for lumpectomy, axillary ultrasound (AUS) combined with fine-needle aspiration cytology (FNAC) allowed researchers to detect macrometastases in axillary lymph nodes prior to resection, sparing the patients from subsequent sentinel lymph node biopsy (SLNB). Data were presented at the ASCO Breast Cancer Symposium in a general session titled “Controversies in the Management of the Axilla.”
Bedanta P. Baruah, MD, surgical research fellow, Cardiff University School of Medicine, United Kingdom, explained the findings, which was a 2009 Breast Cancer Symposium Merit Award Recipient. The researchers questioned whether routine pre-lumpectomy AUS-FNAC would spare some patients with early breast cancer from a second procedure to remove metastatic armpit lymph nodes. Axillary clearance is associated with additional morbidity and expense.
Dr Baruah said investigations into other techniques for identifying lymph node metastases preoperatively found them to be “of extremely limited value.” On its own, AUS is also of limited value, he said, because of its high rate of false positives and false negatives. Results from combining AUS with FNAC, however, have been promising. “The main advantage…is that this is a minimally invasive outpatient procedure,” said Dr Baruah.
A review of the literature on AUS-FNAC identified a 2006 study that associated the technique with 99.8% specificity and 21% sensitivity. Previous studies left several questions unanswered: the role of AUS-FNAC in patients undergoing breast conservation surgery, its ability to detect micrometastases, and whether it was associated with a significant learning curve.
The observational study included 274 patients with early stage breast cancer scheduled for lumpectomy from January 2007 to December 2008. The patients’ median age was 60 years; 217 had invasive ductal cancer and 34 had invasive lobular cancer (tumors in the remaining 24 were categorized as “other”). Prior to surgery, patients underwent ipsilateral axillary ultrasound, performed by a dedicated breast radiologist. Suspicious nodes were aspirated during surgery, and the aspirate was examined by a cytopathologist for cancer cells. Women with positive nodes immediately underwent axillary clearance.
Criteria for Suspicious Nodes
Cortical thickness >3 mm
Longitudinal: transverse axis ratio of <2
Ill-defined nodal margins
Concentric thickening with compression
Or obliteration of nodal hilum
Focal/eccentric cortical thickening
AUS-FNAC detected lymph node macrometastases in 17 women; 217 patients were identified as node-negative. On final pathology, 57 women had nodal metastases, which means AUS-FNAC successfully identified lymph node macrometastases in 29.8% of node-positive patients. “Using AUS-FNAC, all 217 patients were correctly identified as node-negative,” Dr Baruah said. “We did not have any false positives, which is quite important.”
Investigators calculated that AUS-FNAC had a 29.8% sensitivity rate and a 100% specificity rate in the study. Positive predictive value was 100% and negative predictive value was 84.4%. Accuracy, based on the percentage of patients whose final node status was correctly identified preoperatively, was 85.4%. As a result, 6.2% of patients avoided unnecessary SLNB.
No patients suffered complications from the procedure. The main drawback, which the authors described as “small,” is that AUS-FNAC failed to detect micrometastases preoperatively. Dr Baruah concluded, “All patients eligible for breast conservation surgery should have a preoperative AUS-FNAC, preferably performed by a trained breast radiologist.” Abstract No. 22.