Accuracy of HER2 Status Determination on Breast Core-needle Biopsies (Immunohistochemistry, FISH, CISH and SISH vs FISH)

Laurent Arnould; Pascal Roger; Gaëtan MacGrogan; Marie-Pierre Chenard; André Balaton; Sophie Beauclair; Frederique Penault-Llorca

Disclosures

Mod Pathol. 2012;25(5):675-682. 

In This Article

Materials and Methods

Study Design

This French multicenter, cross-sectional, histopathological study was based on the diagnostic core-needle biopsies and surgical specimens, in women suffering from a previously untreated early-stage breast cancer.

Twenty histopathological laboratories (10 cancer centers, 5 university hospitals and 5 private laboratories) involved in breast cancer diagnosis participated in the study. They used immunohistochemistry and were trained to perform CISH assay. There were also four reference centers (2 cancer centers, 1 university hospital and 1 private laboratory) experienced in FISH and CISH and in the analysis of discordant cases. Among these 24 centers, 18 performed SISH assays. Participating centers had to recruit patients suffering, at first diagnosis, from non-metastatic, invasive breast carcinoma that had not been treated before surgical removal, and whose core-needle biopsies and surgical specimens were available at the center. Samples had to contain sufficient invasive tumor material to perform the different study assays, and histological tissues were fixed, depending of the structure's procedures, by neutral buffered formalin, alcohol-formalin-acetic acid, Hollande's fixative or alcohol-formalin.

It was decided to make an a priori selection of the patients, to reach significance in the statistical analysis taking into account the estimation that only 15% of patients with early breast cancer have an HER2-positive status. Patient screening was based on immunohistochemistry results obtained on surgical specimens and each center had to recruit 5–6 patients scored 3+, 2 patients scored 2+ and 3 patients scored 0/1+, by immunohistochemistry. The retrospective deadline for the oldest selected cases was fixed at 1 January 2003. If there were insufficient retrospective cases, prospective cases could be included. Collected data were patient and tumor characteristics, HER2 evaluation method (fixative procedures, type of autostainers, antigens retrieval methods, types of antibodies, with the interpretation guideline used for immunohistochemistry; CISH, SISH or FISH procedures for hybridization techniques) according to the type of specimen (core-needle biopsy or surgical specimens), and results.

In accordance with French legislation regarding non-interventional studies, the study protocol was approved by the 'Comité Consultatif sur le Traitement de l'Information en Matie`re de Recherche dans le Domaine de la Santé' (Consultative Committee on Information Processing for Research in the Field of Health) and validated by the 'Commission Nationale de l'Informatique et des Libertés' (Independent administrative authority protecting privacy and personal data), which guarantees subject confidentiality.

Study Objectives

The primary study objective was to assess the concordance of HER2 status determined by immunohistochemistry, CISH and SISH, performed on core-needle biopsies, with FISH results obtained on surgical specimens. The scoring was performed according to different guidelines used: test performed in routine practice by the participant centers (Herceptest (pathologists' scoring); cutoff of 10% for 3+ category),[16] ASCO/CAP criteria (cutoff of 30% for 3+ category),[2] and GEFPICS (Groupe d'Etude des Facteurs Pronostiques par Immunohistochimie dans le Cancer du Sein) criteria (cutoff of 60% of positive cells intermediate intensity for 2+ category).[8] The secondary objectives of the study were to assess the concordance of HER2 status assessed on core-needle biopsies with that determined on surgical specimens (by immunohistochemistry, SISH, CISH and FISH), and to describe the clinical and histopathological characteristics of patients and tumors.

Statistical Methods

In all, 220 enrolled patients were needed to obtain 196 evaluable cases with the hypothesis of 15% discordant cases between CISH results on coreneedle biopsies and FISH results on surgical specimens, using a two-sided 95% confidence interval with 5% precision.

The percentages of discordant cases between immunohistochemistry, CISH and SISH on preoperative specimens, and FISH on surgical specimens were described with their 95% confidence intervals as well as sensitivity, specificity, false positive and negative rates, and positive and negative predictive values. Concordance results for immunohistochemistry were compared between different interpretation guidelines, using coefficient of correlation k, as well as the correlation results with CISH and SISH. The same statistical methods were used for concordance between results of each method according to the type of tested sample (core-needle biopsies vs surgical specimens). Clinical and pathological characteristics of patients were described in the overall studied population.

All tests were two-sided with an a risk at 5%. Statistical analyses were performed using SAS Version 8.2 (SAS Institute, Cary, NC, USA).

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