. Author manuscript; available in PMC: 2015 Jul 6.

Published in final edited form as: Cancer Prev Res (Phila). 2013 Oct 29;6(11):1194–1211. doi: 10.1158/1940-6207.CAPR-13-0207

Table 2. Effects of a 3-week exposure to leptin or estradiol on later mammary carcinogenesis in nulliparous and parous rats.

Nulliparous rats were administered DMBA at 50 days of age and 3 weeks later treated with vehicle, leptin or estradiol for 2 weeks. Parous rats were also administered DMBA at 50 days of age, and mated 2 weeks later. Pregnant dams were exposed to leptin or estradiol between days 8 of and 19 of gestation. Values for tumor latency and multiplicity are expressed as the mean ± SEM. Total tumor incidence values are expressed as the number of rats with mammary tumors per group, and between weeks 0–12 or 13–22 after DMBA as number and percentage of all tumors per group. Values marked with a different letter are significantly different from each other: p<0.05.

Treatment	Tumor incidence (%) Weeks after treatment			Tumor multiplicity (mean±SEM)	Tumor latency (weeks) (mean±SEM)
Treatment	0–22	0–12	13–22	Tumor multiplicity (mean±SEM)	Tumor latency (weeks) (mean±SEM)
Nulliparous rats
Control	17/29 59%	7/17 41%	10/17^a 59%	1.88 ± 0.40	13.29 ± 1.09
Leptin	14/28 50%	11/14 79%	3/14^b 21%	1.43 ± 0.14	11.14 ± 1.22
Estradiol	22/41 54%	5/22 23%	17/22^c 77%	1.73 ± 0.24	14.9 ± 0.84
Parous rats
Control	14/43^b 32%	13/14 93%	1/14^a 7%	1.93 ± 0.29	7.07 ± 0.76^a
Leptin	26/40^a 65%	14/26 54%	12/26^b 46%	1.33 ± 0.12	12.27 ± 1.11^b
Estradiol	19/42^a,b 45%	9/19 47%	10/19^b 53%	1.37 ± 0.18	12.31 ± 1.38^b