Table 1.

Studies on tamoxifen (20 mg a day) as a breast cancer preventive agent.

Study	Number of women	Median follow up (mo)	Relative Risk of ER positive cancer	Population
Royal Marsden trial [15]	2,471	158	0.6 (0.43-0.86)	Positive family history
NSABP P-1 study [16]	13,388	84	0.38 (0.28-0.5)	Gail score ≥1.66%
Italian Study [17]	5,408	132	0.77 (0.51-1.16)	Healthy post hysterectomy
IBIS-1 [18]	7,139	96	0.66 (0.50-0.87)	High risk by age and family history