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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
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
ID
1192712
Author(s)
Viale, Giuseppe; Giobbie-Hurder, Anita; Regan, Meredith M; Coates, Alan S; Mastropasqua, Mauro G; Dell'Orto, Patrizia; Maiorano, Eugenio; MacGrogan, Gaëtan; Braye, Stephen G; Ohlschlegel, Christian; Neven, Patrick; Orosz, Zsolt; Olszewski, Wojciech P; Knox, Fiona; Thürlimann, Beat; Price, Karen N; Castiglione-Gertsch, Monica; Gelber, Richard D; Gusterson, Barry A; Goldhirsch, Aron; Breast International Group Trial 1-98
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
Journal
Journal of clinical oncology
Volume
26
Number
34
Pages / Article-Number
5569-75
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 LI 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.
