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Table 1 Effect of estriol on mammary carcinogenesis

From: Prevention of mammary carcinogenesis by short-term estrogen and progestin treatments

Treatment

Duration

Mammary cancer incidence

Rats with mammary cancer (%)

Average number of cancers per rat

Control

3 weeks

8/10

80

1.7 ± 0.4

30 mg estriol

1 week

10/12

83

1.6 ± 0.3

200 μg estriol

1 week

11/11

100

1.7 ± 0.3

30 mg estriol + 30 mg progesterone

1 week

7/12

58

1.2 ± 0.3

200 μg estriol + 30 mg progesterone

1 week

9/12

75

1.6 ± 0.3

30 mg estriol

3 weeks

7/11

64

1.0 ± 0.3

200 μg estriol

3 weeks

9/12

75

1.6 ± 0.3

30 mg estriol + 30 mg progesterone

3 weeks

3/12*

25

0.4 ± 0.2*

200 μg estriol + 30 mg progesterone

3 weeks

9/11

82

2.0 ± 0.4

  1. Rats were treated with N-methyl-N-nitrosourea at 7 weeks of age. At 9 weeks of age, the rats were treated with hormones for 1 or 3 weeks. Control rats received empty silastic capsules. *P < 0.05 compared with controls.