Table 6.

Effect of estradiol plus progesterone treatment before MNU exposure

Treatment	Mammary cancer incidence	Percent of rats with mammary cancer	Average number cancers per rat
Control	6/11	55	0.7  ±  0.2
30 mg of E plus 30 mg of P	0/10	0*	0†
60 mg of E plus 30 mg of P	2/12	17*	0.2  ±  0.2‡
200 μg of E plus 30 mg of P	1/15	7*	0.1  ±  0.1§

At 7 weeks of age, rats were treated with E plus P for 2 weeks. At 14 weeks of age, they were treated with MNU. 

^*P < 0.007 compared to control. 

^†P < 0.001 compared to control. 

^‡P < 0.03 compared to control. 

^§P < 0.005 compared to control.