Abstract
Preoperative differentiation between limited (pN1; 1–3 axillary metastases) and advanced (pN2–3; ≥4 axillary metastases) nodal disease can provide relevant information regarding surgical planning and guiding adjuvant radiation therapy. The aim was to evaluate the diagnostic performance of preoperative axillary ultrasound (US) and breast MRI for differentiation between pN1 and pN2–3 in clinically node-positive breast cancer. A total of 49 patients were included with axillary metastasis confirmed by US-guided tissue sampling. All had undergone breast MRI between 2008–2014 and subsequent axillary lymph node dissection. Unenhanced T2-weighted MRI exams were reviewed by two radiologists independently. Each lymph node on the MRI exams was scored using a confidence scale (0–4) and compared with histopathology. Diagnostic performance parameters were calculated for differentiation between pN1 and pN2–3. Interobserver agreement was determined using Cohen’s kappa coefficient. At final histopathology, 67.3% (33/49) and 32.7% (16/49) of patients were pN1 and pN2–3, respectively. Breast MRI was comparable to US in terms of accuracy (MRI reader 1 vs US, 71.4% vs 69.4%, p = 0.99; MRI reader 2 vs US, 73.5% vs 69.4%, p = 0.77). In the case of 1–3 suspicious lymph nodes, pN2–3 was observed in 30.4% on US (positive predictive value (PPV) 69.6%) and in 22.2–24.3% on MRI (PPV 75.7–77.8%). In the case of ≥4 suspicious lymph nodes, pN1 was observed in 33.3% on US (negative predictive value (NPV) 66.7%) and in 38.5–41.7% on MRI (NPV 58.3–61.5%). Interobserver agreement was considered good (k = 0.73). In clinically node-positive patients, the diagnostic performance of axillary US and breast MRI is comparable and limited for accurate differentiation between pN1 and pN2–3. Therefore, there seems no added clinical value of preoperative breast MRI regarding nodal staging in patients with positive axillary US.
Highlights
The axillary lymph node status in breast cancer patients provides relevant information regarding treatment planning and prognosis[1,2]
With increasing use of neoadjuvant systemic therapy (NST) and the advantage of possible downstaging of the axilla, alternative approaches are proposed for the axillary lymph node staging, such as sentinel lymph node biopsy (SLNB), marking axillary lymph nodes with radioactive iodine seed (MARI), targeted axillary dissection (TAD), and combining radioactive iodine seed localisation in the axilla with the sentinel node procedure (RISAS), all to avoid axillary lymph node dissection (ALND) associated comorbidities[6,7,8,9]
In clinically node-negative patients treated with primary surgery, the role of a complementary ALND in sentinel node-positive breast cancer patients has been addressed in previous trials, such as the ACOSOG Z0011 and AMAROS11,12
Summary
The axillary lymph node status in breast cancer patients provides relevant information regarding treatment planning and prognosis[1,2]. Preoperative differentiation between limited (pN1; i.e., 1–3 axillary lymph node metastases) and advanced axillary nodal disease in breast cancer patients can provide relevant information regarding the surgical planning and guiding adjuvant radiation therapy. The second aim of this study was to evaluate whether an additional preoperative standard breast MRI is of added clinical value in patients with [1,2,3] suspicious axillary lymph nodes on US for differentiation between pN1 and pN2–3
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