Publication
Title
Mitotic count can predict tamoxifen benefit in postmenopausal breast cancer patients while Ki67 score cannot
Author
Abstract
Background: Controversy exists for the use of Ki67 protein expression as a predictive marker to select patients who do or do not derive benefit from adjuvant endocrine therapy. Whether other proliferation markers, like Cyclin D1, and mitotic count can also be used to identify those estrogen receptor alpha (ER alpha) positive breast cancer patients that derive benefit from tamoxifen is not well established. We tested the predictive value of these markers for tamoxifen benefit in ER alpha positive postmenopausal breast cancer patients. Methods: We collected primary tumor blocks from 563 ER alpha positive patients who had been randomized between tamoxifen (1 to 3 years) vs. no adjuvant therapy (IKA trial) with a median follow-up of 7.8 years. Mitotic count, Ki67 and Cyclin D1 protein expression were centrally assessed by immunohistochemistry on tissue microarrays. In addition, we tested the predictive value of CCND1 gene copy number variation using MLPA technology. Multivariate Cox proportional hazard models including interaction between marker and treatment were used to test the predictive value of these markers. Results: Patients with high Ki67 (>= 5%) as well as low (<5%) expressing tumors equally benefitted from adjuvant tamoxifen (adjusted hazard ratio (HR) 0.5 for both groups)(p for interaction 0.97). We did not observe a significant interaction between either Cyclin D1 or Ki67 and tamoxifen, indicating that the relative benefit from tamoxifen was not dependent on the level of these markers. Patients with tumors with low mitotic count derived substantial benefit from tamoxifen (adjusted HR 0.24, p < 0.0001), while patients with tumors with high mitotic count derived no significant benefit (adjusted HR 0.64, p = 0.14) (p for interaction 0.03). Conclusion: Postmenopausal breast cancer patients with high Ki67 counts do significantly benefit from adjuvant tamoxifen, while those with high mitotic count do not. Mitotic count is a better selection marker for reduced tamoxifen benefit than Ki67.
Language
English
Source (journal)
BMC cancer. - London
Publication
London : 2018
ISSN
1471-2407
Volume/pages
18 (2018) , 11 p.
Article Reference
761
ISI
000439700100006
Pubmed ID
30041599
Medium
E-only publicatie
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
Faculty/Department
Research group
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identification
Creation 07.09.2018
Last edited 17.10.2021
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