Concordance between core needle biopsy and surgical excision specimens for Ki-67 in breast cancer - a systematic review of the literature.

A systematic review was performed to assess concordance of measurement of Ki-67 between core needle biopsy (CNB) samples and surgical excision (SE) samples in patients with invasive breast cancer. MEDLINE and Embase databases were searched. Studies were eligible if performed within the last 10 years; included quantitative measurement of Ki-67 in both CNB and SE samples with no prior breast cancer treatment; measured concordance between two samples; and had full text available. A total of 22 studies, including 5982 paired CNB and SE samples on which Ki-67 was measured, were appraised. Overall, there appeared to be concordance; however, reliability was unclear. Where given, the Cohen's kappa coefficient (κ) of correlation between samples ranged from 0.261 to 0.712. The concordance rate between CNB and SE where measured as a percentage had a range from 70.3 to 92.7% CONCLUSIONS: Assessment of level of concordance of Ki-67 between CNB and SE samples is hampered by different methodologies. International consensus on Ki-67 measurement is urgently needed.