2009

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

Journal of Clinical Oncology, 20 avril 2009, vol. 27, n°17, 2809-2815

Frederique 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, and Henri Roché

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

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