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. 2008 May-Jun;5(1):22–35.

TABLE 2.

Comparing aromatase inhibitors with tamoxifen

Absolute difference Adverse events
Drug DFS OS Hot flashes Endometrial cancer Thromboembolic events Bone fracture/ osteoporosis Trial
Anastrozole vs. tamoxifen 2.4% 0.3% 36% 0.2%* 4.5%* 11%† ATAC, AIs started immediately postsurgery; 3,215 patients in the anastrozole arm, 3,116 in the tamoxifen arm
Letrozole vs. tamoxifen 1.9% 0.7% 34% 0.2% 2.0%* 5.8%* BIG 01-198, AIs started immediately postsurgery; 4,003 patients in the letrozole arm, 4,007 in the tamoxifen arm
Exemestane vs. tamoxifen 3.5% 0.6% 42% NR 1.9%* 7.4%* IES, AIs started after 2 to 3 yrs of tamoxifen; 2,362 patients in the exemestane arm, 2,372 in the tamoxifen arm

AI=aromatase inhibitors; ATAC=arimidex, tamoxifen alone or in combination; BIG=Breast International Group; DFS=disease-free survival; IES=International Exemestane Study; NR=not reported; OS=overall survival.

*

Difference statistically significant in favor of AI.

†

Difference statistically significant in favor of tamoxifen.

Table should not be used to compare AIs, as trial designs differed. These agents’ comparisons to tamoxifen are valid only in the context of each individual trial.