Ki67 EXPRESSION AND DOCETAXEL EFFICACY IN RECEPTOR POSITIVE PATIENTS

Ki67 Expression and Docetaxel Efficacy in Patients With Estrogen Receptor–Positive Breast Cancer

Frédérique Penault-Llorca, Fabrice André, Christine Sagan, Magali Lacroix-Triki, Yves Denoux, Veronique Verriele, Jocelyne Jacquemier, Marie Christine Baranzelli, Frederic Bibeau, Martine Antoine, Nicole Lagarde, Anne-Laure Martin, Bernard Asselain, Henri Roché

From the Department of Pathology, Centre Jean Perrin, Clermont-Ferrand; Department of Medicine and Translational Research Unit, Institut Gustave Roussy, Villejuif; Department of Pathology, Centre Hospitalier Universitaire, Nantes; Departments of Pathology and Medical Oncology, Institut Claudius Regaud, Toulouse; Department of Pathology, Centre François Baclesse, Caen; Department of Pathology, Centre Paul Papin, Angers; Department of Pathology, Institut Paoli-Calmettes, Marseille; Department of Pathology, Centre Oscar Lambret, Lille; Department of Pathology, Centre Val d'Aurelle, Montpellier; Department of Pathology, Centre Hospitalier Universitaire Tenon; Fédération Nationale des Centres de Lutte Contre le Cancer; Department of Biostatistics, Institut Curie, Paris; and Department of Pathology, Centre Hospitalier Universitaire Brest, Brest, France.

Corresponding author: Frédérique Penault-Llorca, MD, Department of Pathology, Centre Jean Perrin, EA 4233, Université d'Allvergne Clermont 1, 63000 Clermont-Ferrand, France; e-mail: frederique.penault-llorca@cjp.fr.

Purpose The indications of adjuvant chemotherapy for patients with estrogen receptor (ER) –positive breast cancer are controversial. We analyzed the predictive value of Ki67, HER2, and progesterone receptor (PR) expression for the efficacy of docetaxel in patients with ER-positive, node-positive breast cancer.

Patients and Methods Expression of Ki67, HER2, and PR was measured by immunohistochemistry in tumor samples from 798 patients with ER-positive breast cancer who participated in PACS01, a randomized trial that evaluated the efficacy of docetaxel. Risk reduction was evaluated using a Cox model adjusted for age, tumor size, nodal involvement, treatment arm, and biomarkers. The predictive value of biomarkers was assessed by an interaction test. Disease-free survival (DFS) was the primary end point.

Results Ki67, HER2, and PR were expressed in 21%, 9%, and 62% of samples, respectively. Hazard ratios for relapse associated with docetaxel were 0.51 (95% CI, 0.26 to 1.01) in ER-positive/Ki67-positive tumors and 1.03 (95% CI, 0.69 to 1.55) in ER-positive/Ki67-negative tumors (ratio for interaction: 0.53; 95% CI, 0.24 to 1.16; P = .11). Five-year DFS rates were 81% (95% CI, 76% to 86%) and 84% (95% CI, 75% to 93%) in patients with ER-positive/Ki67-negative and ER-positive/Ki67-positive tumors treated with docetaxel and 81% (95% CI, 76% to 86%) and 62% (95% CI, 52% to 72%) in patients with ER-positive/Ki67-negative and ER-positive/Ki67-positive tumors treated with fluorouracil, epirubicin, and cisplatin. No trend for interaction was observed between docetaxel and HER2 (ratio for interaction: 0.83; 95% CI, 0.35 to 1.94; P = .66), nor between docetaxel and PR (ratio for interaction: 0.89; 95% CI, 0.47 to 1.66; P = .71).

Conclusion Ki67 expression identifies a subset of patients with ER-positive breast cancer who could be sensitive to docetaxel treatment in the adjuvant setting.