Prognostic and predictive value of androgen receptor expression in postmenopausal women with estrogen receptor-positive breast cancer: results from the Breast International Group Trial 1–98

Table 3 Multivariable analysis of letrozole versus tamoxifen treatment effect by tumor AR expression

			All monotherapy	AR+	AR−	P-Het^c
	Individuals	Events	HR (95% CI)	HR (95% CI)	HR (95% CI)	P-Het^c
Breast cancer-free interval
Model 1^a	1753	236	0.67 (0.52–0.87)	0.73 (0.55–0.98)	0.49 (0.27–0.87)	0.22
Model 1^a	1753	236	p = 0.003	p = 0.03	p = 0.02
Model 2^b	1697	227	0.57 (0.44–0.75)	0.63 (0.47–0.85)	0.39 (0.21–0.72)	0.16
Model 2^b	1697	227	p < 0.001	p = 0.003	p = 0.002
Disease-free survival
Model 1	1753	401	0.75 (0.62–0.92)	0.80 (0.64–0.99)	0.61 (0.39–0.94)	0.27
Model 1	1753	401	p = 0.005	p = 0.04	p = 0.03
Model 2	1697	388	0.69 (0.56–0.84)	0.73 (0.59–0.92)	0.52 (0.33–0.83)	0.19
Model 2	1697	388	p < 0.001	p = 0.008	p = 0.005

AR expression is defined as ≥ 1% positive, < 1% negative. This analysis is restricted to 1753 patients who received letrozole or tamoxifen monotherapy
^aModel 1: Stratified by receipt of chemotherapy and adjusted for age at randomization, AR expression (all monotherapy analysis only)
^bModel 2: Model 1 + adjusted for tumor size, lymph node involvement, local therapy, ER, PR, HER2, and Ki67 expression
^cP value is from test of heterogeneity of treatment effect in AR+ and AR− cancers

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