TABLE 2.
Updated Results from Major Randomized Controlled Trials of Selective Estrogen Receptor Modulators and Aromatase Inhibitors for Breast Cancer Chemoprevention
| Trial | No. of Participants | Eligibility, High-Risk Criteria for Breast Cancer | Intervention | Median Follow-up (Months) | Breast Cancer Incidence | Breast Cancer Risk Reduction RR or HR (95% CI) |
|---|---|---|---|---|---|---|
| BCPT, 20051 | 13,388 | Age ≥ 35, 5-yr Gail risk score > 1.66% if age 35–59 or ≥ 60 or LCIS | Tamoxifen 20 mg/d × 5 yrs versus placebo | 84 | 3.59 versus 6.29a | 0.57 (0.46–0.70) |
| IBIS-I, 20142 | 7,154 | Age 35–70, 10-fold risk if age 35–39, or 4-fold risk if age 40–44, or 2-fold risk if age 45–70 | Tamoxifen 20 mg/d × 5 yrs versus placebo | 192 | 7.0versus 9.8%b | 0.71 (0.60–0.83) |
| STAR, 20103 | 19,747 | Age ≥ 35, postmenopausal, 5-yr Gail risk score > 1.66% | Raloxifene 60 mg/d versus tamoxifen 20 mg/d × 5 yrs | 81 | 5.02 versus 4.04a | 1.24 (1.05–1.47) |
| MAP.3, 20114 | 4,560 | Age ≥ 35, postmenopausal, 5-yr Gail risk score > 1.66% if age 35–59 or age ≥ 60 or AH, LCIS, DCIS with mastectomy | Exemestane 25 mg/d × 5 yrs versus placebo | 35 | 0.19versus 0.55%c | 0.35 (0.18–0.70) |
| IBIS-II, 20135 | 3,864 | Age 40–70, postmenopausal, 4-fold risk if age 40–44, or 2-fold risk if age 45–59, or 1.5-fold risk if age 60–70 | Anastrozole 1 mg/d × 5 yrs versus placebo | 60 | 2% versus 4%b | 0.47 (0.32–0.68) |
Abbreviations: SERM, selective receptor estrogen modulators; AI, aromatase inhibitor; AH, atypical hyperplasia; BCPT, Breast Cancer Prevention Trial; CI, confidence interval; DCIS, ductal carcinoma-in-situ; HR, hazard ratio; IBIS, International Breast cancer Intervention Study; LCIS, lobular carcinoma in situ; MAP, Mammary Prevention Trial; RR, relative risk; STAR, Study of Tamoxifen and Raloxifene.
aInvasive breast cancer incidence rate/1,000 women.
bAll breast cancers, invasive and noninvasive.
cAnnual incidence of invasive breast cancers.