The sensitivity of pre-operative axillary staging in breast cancer: comparison of invasive lobular and ductal carcinoma.

INTRODUCTION: Axillary ultrasound (AUS) with fine-needle aspiration (FNA) biopsy of abnormal lymph nodes is important for pre-operative staging and planning the surgical management of the axilla. Invasive lobular carcinoma (ILC) metastases are thought to be difficult to detect because the cells are small and on cytology resemble lymphocytes. To investigate this we directly compared the sensitivity of pre-operative axillary staging between ILC and invasive ductal carcinoma (IDC).

METHOD: Consecutive patients that presented in a single breast unit with pure IDC between April 2005 and December 2006 and pure ILC between January 2008 and December 2012 were retrospectively identified from pathology records. Pre-operative axillary ultrasound and FNA biopsy results were compared with post-operative histopathology from the sentinel node biopsy (SNB) or axillary lymph node dissection (ALND).

RESULTS: A total of 275 and 142 axillae were identified in the IDC and ILC groups respectively. In the node positive patients there was no significant difference in the sensitivity of AUS (IDC vs. ILC; 58.7% vs. 52.8%). However, there was a significant difference in the sensitivity of ultrasound-guided FNA biopsy of abnormal nodes (IDC vs. ILC; 98.4% vs. 53.6%; p < 0.001).

CONCLUSION: AUS has comparative sensitivities between IDC and ILC populations. In contrast, FNA biopsy of abnormal axillary nodes is clearly less sensitive in the ILC group. In these patients, who have abnormal AUS, we suggest that a core biopsy is required to improve the pre-operative staging and prevent unnecessary surgical procedures.