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Table 11Results of Chemoprevention Trials—Adverse Effects

StudySubjectsNMedian follow-up (mo)Adverse effects
Treatment Placebo Relative risk (95% CI)
Tamoxifen (20 mg per day)
International Breast Cancer Intervention Study (IBIS-I) (IBIS, 2002)59 Increased breast cancer risk based on family history and other factors.3573 tamoxifen50Thromboembolic event43172.5 (1.5–4.4)
Mean age 50.8 years; 40% using estrogen.3566 placeboPulmonary embolism13101.30 (0.57–2.96)
Deep vein thrombosis2454.79 (1.83–12.54)
Stroke13111.18 (0.53–2.63)
Endometrial cancer1152.2 (0.8–6.06)
All cause death25112.27 (1.12–4.60)
National Surgical Adjuvant Breast and Bowel Project P-1 Study (Fisher et al, 1998)60 Increased breast cancer risk by Gail model; age ≥60 years or risk factors.6576 tamoxifen55Thromboembolic event53NA28NA1.90 (1.20–3.00)
39% <50 years old; <10% using estrogen.6599 placeboPulmonary embolism180.6960.233.01 (1.15–9.27)
Deep vein thrombosis351.34220.841.60 (0.91–2.86)
Stroke381.45240.921.59 (0.93–2.77)
Endometrial cancer362.3150.912.53 (1.35–4.97)
All cause death572.17712.710.81 (0.56–1.16)
Royal Marsden Hospital Trial (Powles et al, 1998)61 Family history of breast cancer <50 years old or in ≥2 relatives.1238 tamoxifen70Thromboembolic event741.74 (0.51–5.94)
Median age 47 years; 26% using estrogen.1233 placeboPulmonary embolism321.49 (0.25–8.93)
Deep vein thrombosis421.99 (0.37–10.86)
Endometrial cancer413.98 (0.46–35.59)
All cause death961.49 (0.53–4.18)
Italian Tamoxifen Prevention Study (Veronesi et al, 1998)62 Women with hysterectomy.2700 tamoxifen46Thromboembolic event741.76 (0.51–5.99)
Median age 51 years; 14% using estrogen.2708 placeboPulmonary embolism111.00 (0.06–16.03)
Deep vein thrombosis632.01 (0.50–8.01)
Stroke951.81 (0.61–5.38)
Endometrial cancerNA
All cause death690.67 (0.24–1.88)
Raloxifene (60 or 120 mg per day)
Multiple Outcomes of Raloxifene Evaluation (Cummings et al, 1999)64 Postmenopausal women with osteoporosis.5129 raloxifene40Thromboembolic event4983.1 (1.5–6.2)
Median age 66.9 years; 10% on estrogen.2576 placeboPulmonary embolism1732.85 (0.83–9.7)
Deep vein thrombosis3853.82 (1.50–9.69)
Endometrial cancer640.8 (0.2–2.7)
All cause deathNA

NA, not available.


Per 1,000 woman-years.


From: 3, Results

Cover of Genetic Risk Assessment and BRCA Mutation Testing for Breast and Ovarian Cancer Susceptibility
Genetic Risk Assessment and BRCA Mutation Testing for Breast and Ovarian Cancer Susceptibility [Internet].
Evidence Syntheses, No. 37.
Nelson HD, Huffman LH, Fu R, et al.

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