Ki67 proliferation in core biopsies versus surgical samples - a model for neo-adjuvant breast cancer studies

BMC Cancer

Research Article

Pär-Ola Bendahl¹  Quinci Romero²  Niklas Loman³  Signe Borgquist³  Marie Klintman³  Carsten Rose³  Dorthe Grabau⁴  Lisa Rydén⁵  Christian Ingvar⁵ 

[1] Department of Oncology, Clinical Sciences, Lund University, Lund, Sweden;Department of Oncology, Skåne University Hospital, Lund, Sweden;Department of Oncology, Skåne University Hospital, Lund, Sweden;Department of Oncology, Clinical Sciences, Lund University, Lund, Sweden;Department of Pathology, Skåne University Hospital, Lund, Sweden;Department of Pathology, Laboratory Sciences, Lund University, Lund, Sweden;Department of Surgery, Skåne University Hospital, Lund, Sweden;Department of Surgery, Clinical Sciences, Lund University, Lund, Sweden;

关键词: core biopsy;    Ki67;    breast cancer;    proliferation;    neo-adjuvant;   

DOI  :  10.1186/1471-2407-11-341

 received in 2011-03-14, accepted in 2011-08-07,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundAn increasing number of neo-adjuvant breast cancer studies are being conducted and a novel model for tumor biological studies, the "window-of-opportunity" model, has revealed several advantages. Change in tumor cell proliferation, estimated by Ki67-expression in pre-therapeutic core biopsies versus post-therapeutic surgical samples is often the primary end-point. The aim of the present study was to investigate potential differences in proliferation scores between core biopsies and surgical samples when patients have not received any intervening anti-cancer treatment. Also, a lack of consensus concerning Ki67 assessment may raise problems in the comparison of neo-adjuvant studies. Thus, the secondary aim was to present a novel model for Ki67 assessment.MethodsFifty consecutive breast cancer cases with both a core biopsy and a surgical sample available, without intervening neo-adjuvant therapy, were collected and tumor proliferation (Ki67, MIB1 antibody) was assessed immunohistochemically. A theoretical model for the assessment of Ki67 was constructed based on sequential testing of the null hypothesis 20% Ki67-positive cells versus the two-sided alternative more or less than 20% positive cells..ResultsAssessment of Ki67 in 200 tumor cells showed an absolute average proliferation difference of 3.9% between core biopsies and surgical samples (p = 0.046, paired t-test) with the core biopsies being the more proliferative sample type. A corresponding analysis on the log-scale showed the average relative decrease from the biopsy to the surgical specimen to be 19% (p = 0.063, paired t-test on the log-scale). The difference was significant when using the more robust Wilcoxon matched-pairs signed-ranks test (p = 0.029). After dichotomization at 20%, 12 of the 50 sample pairs had discrepant proliferation status, 10 showed high Ki67 in the core biopsy compared to two in the surgical specimen (p = 0.039, McNemar's test). None of the corresponding results for 1000 tumor cells were significant - average absolute difference 2.2% and geometric mean of the ratios 0.85 (p = 0.19 and p = 0.18, respectively, paired t-tests, p = 0.057, Wilcoxon's test) and an equal number of discordant cases after dichotomization. Comparing proliferation values for the initial 200 versus the final 800 cancer cells showed significant absolute differences for both core biopsies and surgical samples 5.3% and 3.2%, respectively (p < 0.0001, paired t-test).ConclusionsA significant difference between core biopsy and surgical sample proliferation values was observed despite no intervening therapy. Future neo-adjuvant breast cancer studies may have to take this into consideration.

【 授权许可】

Unknown   
© Romero et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.