Chemoprevention of Breast Cancer: Recommendations and Rationale, Table 1. Predicted Benefits and Harms of 5 Years of Tamoxifen Therapy according to Age and Family History

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Table 1. Predicted Benefits and Harms of 5 Years of Tamoxifen Therapy according to Age and Family History¹

Variable²	Women 45 Years of Age	Women 55 Years of Age	Women 65 Years of Age	Women 75 Years of Age
Predicted 5-year risk of breast cancer, %³
No Family history	0.7	1.1	1.5	1.6
Family history	1.6	2.3	3.2	3.4
Benefits per 1,000 women over 5 y of tamoxifen therapy
Cases of invasive breast cancer avoided, n
No Family history	3-4	5-6	7-8	8
Family history	8	11-12	16	17
Cases of noninvasive breast cancer avoided, n
No Family history	1-2	2	2-3	2-3
Family history	2-3	3-4	4-5	5-6
Hip fractures avoided, n⁴	<1	3	5	15
Harms per 1000 women over 5 y of tamoxifen therapy
Cases of endometrial cancer caused, n⁴	1-2	12	21	"22"
Strokes caused, n⁴	1	3	9	20
Pulmonary emboli caused, n⁴	1-2	4-5	9	18
Cases of deep venous thrombosis caused, n⁴	1-2	1-2	3	4

¹ These estimates are based on the Gail model, outcomes from the Breast Cancer Prevention Trial, and baseline rates of harms from Gail et al.¹³
² No family history = no first-degree relatives with breast cancer; family history = 1 first-degree relative with breast cancer.
³ Based on menarche at 12 years of age, first birth at "22" years of age, and no history of breast biopsy, as calculated from the Gail model.
⁴ Modified from Gail et al.¹³

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Table 1. Predicted Benefits and Harms of 5 Years of Tamoxifen Therapy according to Age and Family History1

Table 1. Predicted Benefits and Harms of 5 Years of Tamoxifen Therapy according to Age and Family History¹