Resumen:
Objectives Sentinel node biopsy (SNB) has become a standard treatment in staging axillary lymph nodes in early breast cancer. However, SNB is an invasive procedure. Breast cancer is frequently characterised by increased 18FDG uptake and many studies have shown encouraging results in detecting axillary lymph node metastases. The aim of this study was to compare SNB and positron emission tomography/computed tomography (PET/CT) imaging, to assess their values in detecting occult axillary metastases.
Methods Forty-nine women (mean age 55-year old) with 50 breast cancer (mean primary tumor size 1.97 cm) and clinically negative axilla were enrolled in the study. 18FDG PET was carried out before surgery, using a PET/CT scanner. In all patients, SNB was carried out after identification through lymphoscintigraphy. Patients underwent axillary lymph nodes dissection (ALND) in cases of positive SNB. The results of PET scan were compared with histopathology of SNB and ALND.
Results In all, 23 out of the 49 patients (47%) had metastases in axillary nodes. The standardized uptake value (SUV) was related to the histological grading (2.6±1.1 in well differentiated vs 3.7±3.1 in poorly differentiated). Sensitivity of FDG-PET scan for detection of axillary lymph node metastases in this series was very low (13%) due to 7 false negative in micrometastases and 6 false negative in immunohistochemistry metastases. Positive predictive value was 75% due to a false positive diagnosis. However, specificity was acceptable (96%).
Conclusions The high specificity of PET/CT imaging indicates that patients who have a PET-positive axilla should have an ALND rather than an SNB for axillary staging. In contrast, FDG-PET showed poor sensitivity in the detection of axillary metastases, confirming the need for SNB in cases where PET is negative in the axilla
