Table I.
Tumor incidence and multiplicity by treatment group
| Treatment | Tumor incidence | Tumor multiplicity | Day of first tumor appearance |
| Cholesterol | 0 (0/10) | NA | NA |
| 17β-Estradiol (E2) | 81.8% (9/11) | 3.1 ± 0.7 | 128 |
| Vitamin C | 0 (0/17) | NA | NA |
| Vitamin C + E2 | 29.4% (5/17)* | 1.6 ± 0.4 | 183 |
| α-naphthoflavone (ANF) | 0 (0/18) | NA | NA |
| ANF + E2 | 0 (0/17)* | NA | NA |
NA, not applicable.
Column one lists the different treatments each group of animals received. The percentage of animals that developed tumors during the 240 day treatment period (tumor incidence) is listed in column two. The symbol indicates ‘*’ indicates a P value <0.05 comparing tumor incidence between the E2 treatment group and the E2 + vitamin C and E2 + ANF treatment groups. P-values were calculated using Fisher's exact test. The number of tumors per tumor-bearing rat (tumor multiplicity) is listed in column three. Column four lists the day of first tumor appearance for animals in each group.