Abstract P1-08-05: The Establishment of Rat Model of Premalignant Breast Disease and Histomorphological Study of Rats’ Premalignant Disease
Authors: Gao DZ , Yu GZ , Ma BZ , Zhang Q , Li L , Li YY. 
Published: April 2011

Abstract
Background:The treatment of breast cancer requires not only a reasonable strategy, but also effective preventive measures. Study of precancerous lesions can help explore the pathogenesis of breast cancer, and its mechanism is important of vesting. In view of long-term progressive pathological process and many co-exsited factors, it is difficult to observe the process in the human being itself, the establishment of a suitable animal model can surve to provide experimental basis for the prevention of premalignancy of breast cancer's transfer mechanism and have a great value.At present, the establishment of breast hyperplasia animal model is mature and unsuccessful for difficulty to determine the end of experiment.
Methods: 54 SD rats were randomly divided into 7 groups. Observation of GroupII-VII last for 32 weeks.
GroupI:blank control ,NS 1ml ig in the first day,0.5 ml NS intraperitoneal injection at the 2nd -25th days ,then stop for 5 days .30 days is one cycle ,observe 7 cycles.
GroupII: DMBA only.DMBA ig in the first day with the dose of 10mg/kg DMBA GroupIII: DMBA +hormone sequential 5 days.DMBA ig in the first day with the dose of 10mg/kg DMBA ,estradiol benzoate intraperitoneal injection with the dose of 0.5mg/kg.day at the 1st -3rd days. Progestin intraperitoneal injection with the dose of 4mg/kg.day at the 4th day. one cycle was 5 days
GroupIV: DMBA +hormone sequential 30 days.DMBA ig in the first day with the dose of 10mg/kg DMBA ,estradiol benzoate intraperitoneal injection with the dose of 0.5mg/kg.day at the 1st -21st days. Progestin intraperitoneal injection with the dose of 4mg/kg.day at the 22nd-25th days. one cycle was 30 days
Group V:MNU only; DMBA only; MNU ig in the first day with the dose of 5mg/kg .
Group VI: MNU +hormone sequential 5 days.MNU ig in the first day with the dose of 5mg/kg, estradiol benzoate intraperitoneal injection with the dose of 0.5mg/kg.day at the 1st -3rd days. Progestin intraperitoneal injection with VII: MNU +hormone sequential 30 days .,MNU ig in the first day with the dose of 5mg/kg, ,estradiol benzoate intraperitoneal injection with the dose of 0.5mg/kg.day at the 1st -21st days. Progestin intraperitoneal injection with the dose of 4mg/kg.day at the 22nd-25th days. one cycle was 30 days.
After the 14th week, one pair of breast of every group was taken out to perform the histomorphological changes until all the rats were executed in the 32nd week.
Result:The total incidence of premalignant breast disease of DMBA group was 47%, while MNU group 8%,with statistical significance. No statistical significan was observed within the subgroup of DMBA. Most of premalignant lesions occurred during the 20th to 28th weeks. See Table 1.
Pathological results of 7 Groups
Discussion
MNU is not fit for inducing the premalignant lesions of SD rats. DMBA is a better medicine to observe the premalignant lesions of SD rats.
The 20-28 weeks is the best interval to observe the premalignant lesions.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-08-05.