Assessment of HER2 status in breast cancer biopsies is not affected by accelerated tissue processing

Abstract

Aims

To establish whether core needle biopsy (CNB) specimens processed with an accelerated processing method with short fixation time can be used to accurately determine HER2 status of breast cancer.

Methods and results

A consecutive case series from two high volume breast clinics was created. We compared routine HER2 immunohistochemistry (IHC) assessment between accelerated processing CNB specimens and routinely processed postoperative excision specimens. Additional amplification-based testing was performed in cases with equivocal results. The formalin fixation time was less than 2 hours and between 6 and 72 hours, respectively. Fluorescent in situ hybridization and multiplex ligation-dependent probe amplification were used for amplification testing.

One hundred and forty-four cases were included, 15 of which were HER2 positive on the routinely processed excision specimens. On the CNB specimens, 44 were equivocal on IHC and required an amplification-based test. Correlation between the CNB specimens and the corresponding excision specimens was high for final HER2 status, with an accuracy of 97% and a kappa of 0.85.

Conclusions

HER2 status can be reliably determined on CNB specimens with accelerated processing time using standard clinical testing methods. Using this accelerated technology, the minimum six hours of formalin fixation which current guidelines consider necessary, can safely be decreased. This allows for a complete and expedited histology-based diagnosis of breast lesions in the setting of a one-stop-shop, same-day breast clinic.

This article is protected by copyright. All rights reserved.

http://ift.tt/2FgIO63