TITLE:
Sensitivity and Specificity of Pre-Operative Staging of the Axilla When Using OSNA in Breast Cancer Patients
AUTHORS:
Jonathan D. Horsnell, Kashif Choudhry, Daniel Urriza-Rodriguez, Alex Valencia, Zenon Rayter
KEYWORDS:
Breast Cancer, Axillary Metastases, Ultrasound, OSNA
JOURNAL NAME:
Advances in Breast Cancer Research,
Vol.5 No.3,
June
28,
2016
ABSTRACT: Introduction:All patients with a new diagnosis of breast cancer undergo
pre-operative axillary ultrasound (US) and biopsy to identify axillary metastases.
The efficacy of this approach at identifying metastatic disease is particularly
important if an intra-operative technique of assessment is used. This paper is
the first to report the sensitivity and specificity of pre-operative axillary
ultrasound within the context of the routine use of OSNA (one step nucleic acid
amplification) (Sysmex, Japan), a molecular assay technique for the
intra-operative analysis of axillary lymph nodes. This knowledge will help
counsel patients prior to the procedure and inform economic analysis of the
implications of this approach. Method: Consecutive patients diagnosed with
invasive breast cancer between July 2009 and February 2012 at a single centre
were identified by interrogation of MDT (multi disciplinary team) and surgical
databases and a prospective database of all patients undergoing OSNA analysis.
A standardised data collection sheet was used to record tumour characteristics
and the nodal stage for each patient. These results were used to document the
efficacy of preoperative US and biopsy of the axilla in comparison to
intraoperative OSNA analysis. The data were then compared between two groups of
patients, those whose nodes had been assessed using OSNA (the OSNA group) and
those nodes had been tested using standard histopathological examination (the
non-OSNA group). Results: A total of 377 eligible patients were identified.
Within the OSNA group (n = 240) the sensitivity of pre-operative axillary US
was 29% which rose to 41% when micro-metastases were excluded. A specificity
and positive predictive value of 100% was recorded. The negative predictive
value was 74%. There were no significant differences to the efficacy when the
nodes were assessed with standard histopathology. The detection rate of
micro-metastases was significantly higher in the OSNA group (P = 0.001), but
there was no statistically significant difference in those with
macro-metastases (P = 0.457). Conclusions: There are no significant differences
in the sensitivity and specificity achieved by pre-operative axillary US when
compared to either post operative histopathology or OSNA molecular analysis as
the gold standard. OSNA, however, does increase the detection of
micro-metastases.