· Study’s design and patient selection:
This was a prospective study,
approved by our institutional ethics committee in 12/2011,
and included 182 patients referred to the Institute of Cancer of São Paulo with newly diagnosed primary invasive breast cancer from April 2012 to April 2014.
After signing the informed consent form,
all patients were submitted to ultrasound evaluation of the ipsilateral axilla and fine needle aspiration (FNA).
Exclusion criteria were as follow: patients with ductal carcinoma in situ,
patients who had done neoadjuvant treatment before axillary evaluation and/or patients with previous history of breast cancer.
· Examination technique,
axillary lymph node characterization and selection:
Radiologists with at least two years of experience in breast imaging evaluated the ipsilateral axilla with a high frequency transducer ultrasound machine.
Patients were in supine position with hands under head.
We evaluated axillary levels I,
II and III in two orthogonal axes from the axilla base to the apex and from the posterior axillary line to the medial region of the pectoral muscles.
Axillary levels were definded as: level I inferolateral to pectoralis minor,
level II posterior to pectoralis minor and level III superomedial to pectoralis minor.
The radiologist decided which lymph node to biopsy according to the following criteria,
in descending order of priority: lymph nodes with ultrasound suspicious characteristics,
defined as those with cortical thickening equal or greater than 3 mm,
any asymmetric or nodular cortical thickening,
partial or complete fatty hilum obliteration,
round morphology,
presence of calcifications,
espiculated or ill defined margins,
regardless of cortical thickening.
In patients whose lymph nodes did not meet the suspicion criteria,
lymph nodes located in the axilla base and closer to the breast were chosen,
more common location of the sentinel lymph nodes.
If lymph nodes were not found in that location,
we performed FNA of the lymph node in axillary level I,
closer to the axilla base.
· Fine needle aspiration technique:
After local asepsis,
the thickest portion of the lymph node cortical was punctured with a 23G needle attached to a syringe of 10ml to obtain samples for cytological evaluation.
Were done one,
two or three samples (syringes) separated for each node.
The material was sent to cytological analysis.
· Statistical analysis:
Categorical data are presented as percentages and were tested usingPearson χ2 test and Fisher exact test,
if applicable.
Continuous variables were tested for normality with the Kolmogorov-Smimov test and are expressed as medians and interquartile ranges or as the mean±SD as applicable.We compared these variables using the Mann-Whitney U test.