Author/Editor		Viale, Giuseppe; Giobbie-Hurder, Anita; Regan, Meredith M; Coates, Alan S; Mastropasqua, Mauro G; Dell'Orto, Patrizia; Maiorano, Eugenio; MacGrogan, Gaetan; Braye, Stephen G; Čufer, Tanja
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
Type		članek
Source		J Clin Oncol
Vol. and No.		Letnik 26, št. 34
Publication year		2008
Volume		str. 5569-75
Language		eng
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.
Descriptors		ANTINEOPLASTIC AGENTS ANTINEOPLASTIC AGENTS, HORMONAL BREAST NEOPLASMS CHEMOTHERAPY, ADJUVANT COHORT STUDIES KI-67 ANTIGEN NITRILES POSTMENOPAUSE PREDICTIVE VALUE OF TESTS PROGNOSIS PROPORTIONAL HAZARDS MODELS TAMOXIFEN TRIAZOLES