Axillary US Helps Assess Nodal Burden in Breast Cancer

Preoperative axillary ultrasound may help identify women with breast cancer who have a lower burden of lymph node disease and may be suitable for less extensive surgery. A retrospective study in the British Journal of Radiology assessed whether ultrasound could distinguish limited nodal involvement from more advanced disease before surgery. The analysis included women treated at a UK hospital who had biopsy-confirmed axillary metastases and later underwent axillary lymph node dissection. The number of abnormal nodes seen on ultrasound was closely linked to the final pathological findings. Tumour size also differed between groups. The results support ultrasound as a risk assessment tool, but not as the sole basis for treatment decisions.

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Study Design and Patient Selection

The analysis used records from York Hospital collected between January 2023 and December 2024. Patients were included when axillary ultrasound found non-palpable abnormal lymph nodes, biopsy confirmed metastasis and axillary lymph node dissection provided the final nodal stage. Women were excluded if they had received neoadjuvant treatment, had metastatic disease at diagnosis, were not fit for surgery or did not undergo surgery.

Ultrasound examined all three axillary nodal levels. A lymph node was considered abnormal when its outer layer was thicker than 3 mm or its fatty centre was absent. The most suspicious node was sampled under ultrasound guidance. Final pathology classified one to three involved nodes as pN1 disease and four or more as pN2 or pN3 disease.

Among 193 patients with abnormal ultrasound findings, 142 had a positive biopsy. After exclusions, 77 women remained in the main analysis, while complete ultrasound node counts were available for 71. Their average age was 64 years. Most presented with symptoms rather than through screening. Final pathology classified 33 patients as pN1 and 44 as pN2 or pN3. The median number of nodes removed during surgery was 18. The number removed varied widely between patients. Most tumours were invasive ductal cancers of no special type, and most were hormone receptor-positive and HER2-negative.

Node Count Provides the Clearest Signal

The number of abnormal nodes seen before surgery differed clearly between the two pathological groups. Women with pN1 disease had an average of about one and a half suspicious nodes on ultrasound. Those with pN2 or pN3 disease had just over three. Tumours were also smaller in the lower-burden group, averaging 36.5 mm compared with 58.8 mm in women with more extensive nodal involvement.

When one or two abnormal nodes on ultrasound were used to predict pN1 disease, the method identified 87.1% of lower-burden cases. Its overall accuracy was 69%. However, specificity was only 55%, meaning that some women with more extensive disease were incorrectly placed in the lower-burden group.

Using a stricter threshold of one abnormal node improved specificity to 72.5% and reduced false-positive results. Sensitivity fell to 67.7%, while overall accuracy remained similar at 70.4%. A model combining ultrasound node count with tumour size also classified about 70% of patients correctly.

More than two abnormal nodes on ultrasound was the strongest independent predictor of pN2 or pN3 disease. It was linked to sixfold higher odds of more extensive nodal involvement. Tumour size above 5 cm showed only a non-significant trend, and there was no significant interaction between tumour size and node count.

Ultrasound May Support Less Extensive Surgery

Axillary lymph node dissection has long been used to stage and control breast cancer, but it can cause lymphoedema, pain, sensory loss and reduced arm movement. Targeted axillary dissection removes the biopsy-confirmed metastatic node together with sentinel nodes and is linked to fewer surgical complications. Preoperative ultrasound may therefore help identify women who could be assessed for this less extensive approach.

The results do not establish that targeted axillary dissection can safely replace full dissection. Ultrasound findings were collected during routine care and did not determine the surgery performed. The safety of reducing surgery and its effect on cancer outcomes still need confirmation in prospective trials. Ultrasound should therefore support multidisciplinary assessment rather than decide treatment on its own.

Several limitations affect interpretation. The work was retrospective, came from one centre and included a relatively small number of patients. Some diagnostic estimates had wide confidence intervals, and ultrasound interpretation depends on the operator. Several thresholds and models were tested, so the results should be considered exploratory.

The cohort included only women with biopsy-confirmed node-positive disease who underwent full axillary dissection. This selected population may not reflect women with clinically negative nodes or those managed with less invasive surgery. All participants were Caucasian women, which also limits wider application of the findings. Larger prospective studies are needed to confirm the imaging thresholds and define how ultrasound should be combined with other clinical and pathological information.

Preoperative axillary ultrasound can help separate lower from higher lymph node burden in women with biopsy-confirmed node-positive breast cancer. The number of abnormal nodes showed the clearest link with final pathology, while tumour size added less information in the combined model. Ultrasound performed best in identifying lower-volume disease, although misclassification remained possible. It may therefore support risk assessment and multidisciplinary selection for less extensive axillary surgery, but it should not guide treatment alone. Prospective validation is needed before ultrasound thresholds can be used routinely to replace axillary lymph node dissection.

Source: British Journal of Radiology

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