Table 5

Effect of the duration of estradiol plus progesterone treatment on mammary carcinogenesis

TreatmentMammary cancer incidencePercent of rats with mammary cancerAverage number cancers per rat
Control8/9881.6  ±  0.2
30 mg of E plus 60 mg of P, 1 week1/616*0.2  ±  0.2
30 mg of E plus 60 mg of P, 2 weeks0/70*0
30 mg of E plus 90 mg of P, 1 week0/80*0
  • Rats were treated with MNU at 7 weeks of age. At 9 weeks of age, the rats were treated with E plus P for 1 or 2 weeks. 

  • * P < 0.005 compared to control. 

  • P < 0.001 compared to control.