%0 Journal Article
%T Obesity promotes 7,12-dimethylbenz(a)anthracene-induced mammary tumor development in female zucker rats
%A Reza Hakkak
%A Andy W Holley
%A Stewart L MacLeod
%A Pippa M Simpson
%A George J Fuchs
%A Chan Jo
%A Thomas Kieber-Emmons
%A Soheila Korourian
%J Breast Cancer Research
%D 2005
%I BioMed Central
%R 10.1186/bcr1263
%X Fifty-day-old female obese (n = 25) and lean (n = 28) Zucker rats were orally gavaged with 65 mg/kg DMBA. Rats were weighed and palpated twice weekly for detection of mammary tumors. Rats were killed 139 days after DMBA treatment.The first mammary tumor was detected in the obese group at 49 days after DMBA treatment, as compared with 86 days in the lean group (P < 0.001). The median tumor-free time was significantly lower in the obese group (P < 0.001). Using the days after DMBA treatment at which 25% of the rats had developed mammary tumors as the marker of tumor latency, the obese group had a significantly shorter latency period (66 days) than did the lean group (118 days). At the end of the study, obese rats had developed a significantly (P < 0.001) greater mammary tumor incidence (68% versus 32%) compared with the lean group. The tumor histology of the mammary tumors revealed that obesity was associated with a significant (P < 0.05) increase in the number of rats with at least one invasive ductal and lobular carcinoma compared with lean rats.Our results indicate that obesity increases the susceptibility of female Zucker rats to DMBA-induced mammary tumors, further supporting the hypothesis that obesity and some of its mediators play a significant role in carcinogenesis.Obesity has been identified as an epidemic in the USA for more than two decades, yet the proportion of overweight and obese adults in the population continues to grow. The most recent data from the 1999¨C2000 National Health and Nutrition Examination Survey (NHANES) [1] showed that almost 65% of adults in the USA are overweight, defined as having a body mass index (BMI) greater than 25 kg/m2. This is a significant increase from the 56% for adults reported as overweight in NHANES III, which was conducted between 1988 and 1994. The prevalence of obesity, defined as a BMI of 30 kg/m2 or greater, also increased dramatically from 23% to 31% during the same period. It is estimated that the prevalence of
%U http://breast-cancer-research.com/content/7/5/R627