Short answer: Both lower invasive breast cancer risk in some women.12 In STAR, reported in the Evista label, about 19,700 postmenopausal women at higher risk took Evista 60 mg or tamoxifen 20 mg daily: invasive breast cancer was 4.4 vs 4.3 per 1,000 women a year. Evista had lower rates of endometrial hyperplasia and blood clots, and more noninvasive breast cancers. Evista also treats osteoporosis; tamoxifen also treats breast cancer.
| Evista | Tamoxifen | |
|---|---|---|
| Approved for | Postmenopausal women: treating and preventing osteoporosis; lowering invasive breast cancer risk with osteoporosis or high risk1 | Breast cancer treatment in women and men; after DCIS surgery; lowering breast cancer incidence in high-risk women2 |
| Dose | 60 mg once daily, any time, with or without food1 | 20 mg daily for 5 years for risk reduction and DCIS; 20 to 40 mg for breast cancer2 |
| STAR: invasive breast cancer | 4.401 | 4.301 |
| STAR: noninvasive breast cancer | 2.121 | 1.541 |
| STAR: uterine cancer / endometrial hyperplasia | 1.21 / 0.901 | 1.99 / 5.421 |
| STAR: deep vein thrombosis / pulmonary embolism | 1.69 / 0.961 | 2.35 / 1.471 |
| STAR: stroke | 1.361 | 1.421 |
| STAR: cataracts | 10.341 | 13.191 |
| Boxed warning | Blood clots, and death from stroke in women with or at risk of heart disease1 | For DCIS and high-risk women: uterine cancers, stroke and pulmonary embolism2 |
STAR was a randomized, double-blind trial of 19,747 postmenopausal women at higher risk of invasive breast cancer, comparing Evista 60 mg with tamoxifen 20 mg daily over 5 years. The Evista label says Evista was not superior to tamoxifen in reducing invasive breast cancer, and that a noninferiority analysis is consistent with Evista potentially losing up to 35% of the tamoxifen effect. Fewer noninvasive breast cancers occurred on tamoxifen.1 Among women with a uterus, hysterectomy was 4.84 vs 13.25 per 1,000 women a year on Evista vs tamoxifen. Deaths were 2.62 vs 2.76.1
Evista's boxed warning covers blood clots and a higher risk of death from stroke seen in women with coronary heart disease or at higher risk of coronary events. It is not approved to treat breast cancer or to lower the risk of noninvasive breast cancer, and it is not recommended before menopause.1 Tamoxifen's boxed warning, for women using it after DCIS or to lower risk, covers uterine cancers, stroke and pulmonary embolism. Its label also warns about liver and eye effects and says not to become pregnant while taking it or for 2 months after.2 Evista is not used by women with current or past blood clots, and tamoxifen is not used after DCIS or for risk reduction by women with past deep vein thrombosis or pulmonary embolism.12
Which, if either, fits is for your prescriber. More detail: Evista side effects, tamoxifen side effects, the Evista and tamoxifen dosing schedules, the Evista and tamoxifen missed-dose pages, Arimidex vs tamoxifen: how do the two breast cancer tablets differ? and Evista vs Fosamax: how do raloxifene and alendronate differ?.