Table 6 Technical comparison between histological procedures and OSNA assay

Tumour topography

Exhaustive study of tissue topography and detection of extracapsular extension

The assay do not enable the study of tumour topography, but adjacent lymph node tissue is analysed by complementary histological procedures

Morphological study

Study of metastatic deposits and isolated neoplastic cells. Minimisation of false positives like benignant epithelial inclusions (exceptional in mediastinal lymph nodes)

The assay do not enable the study of cellular and histological lymph node morphology

Sensibility

Lower limit of detection

More accuracy than histological procedures. Detection of occult micrometastasis

Whole lymph node analysis

Risk of sample bias. Slow and laborious study of whole lymph node

Fast, feasible and accurate whole lymph node analysis. Minimisation of false negatives

KRT19 quantification

Relative quantification of KRT19 expression by digital pathology

Absolute quantification of KRT19 expression that correlates with metastatic foci. The assay also allows the possibility of detecting total tumour load

Assay rapidity/Workflow

Fast analysis of a single intraoperative slide (less than 15 min)

Fast analysis of the whole lymph node (less than 25 min)

Methodology

Standardised procedures. Immunohistochemical scores and histological examination not protocolled

Normalised and standardised protocols. Unbiased results

Cost-effectiveness

Higher cost of time, personnel and resources for diagnostic

Lower cost-effectiveness ratio

Remnant sample

Remnant samples are available for histological and molecular analysis

Remaining lymph node lysates are available for subsequent molecular analysis