Table 1.

Frequencies of breast cancer recurrence and resistance to anti-estrogen therapies in patients with ER+ breast cancer.

Population	Treatment	Effect	Trial/reference
		Follow-up: 5 years 10 years
Early-stage	Adjuvant anastrozole × 5 years	Distant recurrence: 9.8% 19.7%	ATAC (Cuzick et al., 2010)
Post-menopausal	Adjuvant tamoxifen × 5 years	Distant recurrence: 12.5% 24%
		Follow-up: 5 years 8 years
Early-stage	Adjuvant letrozole × 5 years	Recurrence: 14.5% 23.6%	BIG 1-98 (Regan et al., 2011)
Post-menopausal	Adjuvant tamoxifen × 5 years	Recurrence: 18% 28%
Advanced
Post-menopausal	Anastrozole	No clinical benefit: 33%	FIRST (Robertson et al., 2009a)
No prior Tx	Fulvestrant (high-dose regimen)	No clinical benefit: 27.5%
Advanced
Post-menopausal	Exemestane	No clinical benefit: 68.5%	EFECT (Chia et al., 2008)
Progressed on AI	Fulvestrant (loading-dose regimen)	No clinical benefit: 67.8%
		Median follow-up: 5.3 years
Disease-free following	Letrozole	With disease: 2%	MA.17
5 years of adjuvant tamoxifen	Placebo	With disease: 4.9%	(Goss et al., 2008)
		Median follow-up: 2.5 years
Disease-free following	Exemestane	With disease: 9%	NSABP B-33
5 years of adjuvant tamoxifen	Placebo	With disease: 11%	(Mamounas et al., 2008)