Evaluation of Ki-67 Index in Core Needle Biopsies and Matched Breast Cancer Surgical Specimens.

Evaluation of Ki-67 Index in Core Needle Biopsies and Matched Breast Cancer Surgical Specimens.

Arch Pathol Lab Med. 2017 Nov 16;:

Authors: Ahn S, Lee J, Cho MS, Park S, Sung SH

Abstract
CONTEXT: - The Ki-67 index is strongly prognostic and is used as a surrogate marker to distinguish luminal A from luminal B breast cancer types.
OBJECTIVE: - To investigate differences in Ki-67 index between core needle biopsy samples and matched surgical samples in breast cancer.
DESIGN: - We included patients with invasive breast cancer who did not receive neoadjuvant therapy. A total of 89 pairs of core needle biopsies and surgical specimens were collected, and the Ki-67 index was assessed in hot spot areas using an image analyzer. We applied a 14% Ki-67 index to define low versus high groups.
RESULTS: - The Ki-67 index was significantly higher in core needle biopsies than in surgical specimens (P < .001), with a median absolute difference of 3.5%. When we applied 14% as a cutoff, 16 of 89 cases (18%) showed discrepancy. Thirteen cases showed a high Ki-67 index in core needle biopsies but a low Ki-67 index in surgical samples. There were 10 cases (11.2%) that showed discordant luminal A/B types between core needle biopsy and the matched surgical specimen. The reasons for the discordance were poor staining of MIB1 accompanied by fixation issues and intratumoral heterogeneity of the Ki-67 index.
CONCLUSIONS: - A significant difference in the Ki-67 index between core biopsy and surgical specimens was observed. Our findings indicate that it may be better to perform the Ki-67 assay on the core needle biopsy and the surgical specimen than on only one sample.

PMID: 29144790 [PubMed - as supplied by publisher]

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