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Table 3 Effect of estrogen metabolites 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 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
  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 3 weeks. Control rats received empty silastic capsules. *P < 0.05 compared with controls.