Title: Prognostic and predictive value of centrally reviewed Ki-67 labeling index in postmenopausal women with endocrine-responsive breast cancer: results from Breast International Group Trial 1-98 comparing adjuvant tamoxifen with letrozole
Authors: Viale, G *
Giobbie-Hurder, A * ×
Regan, MM
Coates, AS
Mastropasqua, MG
Dell'Orto, P
Maiorano, E
MacGrogan, G
Braye, SG
Ohlschlegel, C
Neven, Patrick
Orosz, Z
Olszewski, WP
Knox, FR
Thürlimann, B
Price, KN
Castiglione-Gertsch, M
Gelber, RD
Gusterson, BA
Goldhirsch, A
Breast International Group Trial 1-98 #
Contributors: Vergote, Ignace
Wildiers, Hans
Paridaens, Robert
Christiaens, Rose
Issue Date: Dec-2008
Publisher: Grune & Stratton
Series Title: Journal of Clinical Oncology vol:26 issue:34 pages:5569-5575
Conference: Annual San Antonio Breast Cancer Symposium edition:30 date:13-16 December 2007
Abstract: Purpose: To evaluate the prognostic and predictive value of Ki-67 labeling index (LI) in a trial comparing letrozole (Let) with tamoxifen (Tam) as adjuvant therapy in postmenopausal women with early breast cancer.
Patients and methods: Breast International Group (BIG) trial 1-98 randomly assigned 8.010 patients to four treatment arms comparing Let and Tam with sequences of each agent. Of 4.922 patients randomly assigned to receive 5 years of monotherapy with either agent, 2.685 had primary tumor material available for central pathology assessment of Ki-67 LI by immunohistochemistry and had tumors confirmed to express estrogen receptors after central review. The prognostic and predictive value of centrally measured Ki-67 LI on disease-free survival (DFS) were assessed among these patients using proportional hazards modeling, with Ki-67 LI values dichotomized at the median value of 11%.
Results: Higher values of Ki-67 LI were associated with adverse prognostic factors and with worse DFS (hazard ratio [HR; high:low] = 1.8; 95% CI, 1.4 to 2.3). The magnitude of the treatment benefit for Let versus Tam was greater among patients with high tumor Ki-67 LI (HR [Let:Tam] = 0.53; 95% CI, 0.39 to 0.72) than among patients with low tumor Ki-67 LI (HR [Let:Tam] = 0.81; 95% CI, 0.57 to 1.15; interaction P = .09).
Conclusion: Ki-67 is confirmed as a prognostic factor in this study. High Ki-67 LI levels may identify a patient group that particularly benefits from initial Let adjuvant therapy.
ISSN: 0732-183X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Gynaecological Oncology
Laboratory of Experimental Oncology
Surgical Oncology
* (joint) first author
× corresponding author
# (joint) last author

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