Estrogen receptor expression and docetaxel efficacy in patients with metastatic breast cancer: a pooled analysis of four randomized trials.
BACKGROUND
Differences in the efficacy of various chemotherapies in patients with estrogen receptor (ER)(+) metastatic breast cancer are not well understood. In the present study, we assessed the efficacy of docetaxel in patients with metastatic breast cancer according to ER expression.


METHODS
The efficacy of docetaxel in terms of the response rate and progression-free survival (PFS) time was analyzed according to ER expression in four randomized trials comparing a docetaxel-based regimen with a nontaxane regimen that included a total of 1,631 patients. The odds ratio for tumor response was estimated with logistic regression and a hazard ratio (HR) for PFS was estimated with Cox proportional hazards models.


RESULTS
ER expression was assessable in 1,037 patients included in these trials (64%). ER was expressed in 601 tumors (58%). Docetaxel was associated with a similarly higher response rate in both patients with ER(+) (odds ratio, 2.90; 95% confidence interval [CI], 1.72-4.87) and patients with ER(-) (odds ratio, 2.55; 95% CI, 1.44-4.51) disease. The lower hazard for disease progression with docetaxel was also similar in ER(+) (HR, 0.82; 95% CI, 0.67-1.00) and ER(-) (HR, 0.86; 95% CI, 0.70-1.07) cancers. The effect of docetaxel was not different in ER(+) and ER(-) disease, in terms of both the response rate and PFS time (interaction test, p = .77 and p = .93).


CONCLUSIONS
Docetaxel produces a higher response rate and lower risk for disease progression to a statistically similar extent in both patients with ER(+) and patients with ER(-) metastatic breast cancer.
Andre
Fabrice
F
Department of Breast Medical Oncology, The University of Texas,M.D. Anderson Cancer Center, Houston, Texas, USA. fandre@igr.fr
Broglio
Kristine
K
Pusztai
Lajos
L
Berrada
Narjiss
N
Mackey
John R
JR
Nabholtz
Jean Marc
JM
Chan
Stephen
S
Hortobagyi
Gabriel N
GN
D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D018572:Disease-Free Survival; D000077143:Docetaxel; D047628:Estrogen Receptor alpha / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D016032:Randomized Controlled Trials as Topic; D043823:Taxoids / Q000627:therapeutic use*
D000970:Antineoplastic Agents; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D043823:Taxoids; D000077143:Docetaxel