Table 1.
Updated results from major randomized controlled trials of selective estrogen receptor modulators (SERMs) and aromatase inhibitors (AIs) for breast cancer preventive therapy
| Trial | No. of participants | Study population | Agents | Breast cancer risk reduction RR or HR (95% CI) | Toxicities compared to controls (Rate per 1000) |
|---|---|---|---|---|---|
| BCPT, 2005 (ref. 5) | 13,388 | Age ≥ 35 years, 5-yr Gail risk score > 1.66% if age 35-59 years or age ≥ 60 years or LCIS | Tamoxifen 20 mg/day × 5 years vs. placebo | 0.57 (0.46–0.70) | Endometrial cancer (2.24 vs. 0.68) |
| Stroke (1.75 vs. 1.23) | |||||
| Thromboembolism (1.90 vs. 1.16) | |||||
| IBIS-I, 2014 (ref. 6) | 7154 | Age 35–70 years, tenfold risk if age 35–39 years or fourfold risk if age 40–44 years or twofold risk if age 45–70 years | Tamoxifen 20 mg/day × 5 years vs. placebo | 0.71 (0.60–0.83) | Endometrial cancer (8.10 vs. 5.59) |
| Stroke (8.38 vs. 7.83) | |||||
| Thromboembolism (13.97 vs. 8.11) | |||||
| STAR, 2015 (refs 7, 100) | 19,490 | Age ≥ 35 years, postmenopausal, 5-year Gail risk score > 1.66% | Raloxifene 60 mg/day vs. Tamoxifen 20 mg/day × 5 years | 1.19 (1.04–1.37)* | Endometrial cancer (1.23 vs. 2.25) |
| Thromboembolism (2.47 vs. 3.30) | |||||
| Cataracts (11.69 vs. 14.58) | |||||
| MAP.3, 2011 (ref. 8) | 4560 | Age ≥ 35 years, postmenopausal, 5-year Gail risk score > 1.66% if age 35–59 years or age ≥ 60 years or AH, LCIS, DCIS with mastectomy | Exemestane 25 mg/day × 5 years vs. placebo | 0.35 (0.18–0.70) | Fractures (66.51 vs. 63.60) |
| Cardiovascular events (47.32 vs. 49.37) | |||||
| IBIS-II, 2014 (ref. 9) | 3864 | Age 40–70 years, postmenopausal, fourfold risk if age 40–44 years or twofold risk if age 45–59 years or 1.5-fold risk if age 60–70 | Anastrozole 1 mg/day × 5 years vs. placebo | 0.47 (0.32–0.68) | Fractures (85.42 vs. 76.65) |
| Cardiovascular events (66.67 vs. 48.87) |
Adapted from Crew ASCO Educational Book, 2015 with permission from the American Society of Clinical Oncology
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, RR relative risk, STAR Study of Tamoxifen and Raloxifene
*Comparing raloxifene to tamoxifen