Table 3

Effect of estrogen metabolites on mammary carcinogenesis

Treatment

Duration

Mammary cancer incidence

Rats with mammary cancer (%)

Average number of cancers per rat

Control

3 weeks

9/12

75

1.3 ± 0.5

2 mg 2-hydroxy estradiol

3 weeks

8/10

80

1.4 ± 0.3

2 mg 2-hydroxy estradiol + 30 mg progesterone

3 weeks

6/10

60

1.5 ± 0.5

2 mg 2-methoxy estradiol

3 weeks

6/10

60

0.7 ± 0.2

2 mg 2-methoxy estradiol + 30 mg progesterone

3 weeks

3/10*

30

0.4 ± 0.2

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 3 weeks. Control rats received empty silastic capsules. *P < 0.05 compared with controls.

Rajkumar et al. Breast Cancer Res 2004 6:R31   doi:10.1186/bcr734