Effect of gonadectomy on carcinogenesis and development of hepatocellular carcinoma induced by chemical substances in rat model

Objective To assess the effects of gonadectomy on carcinogenesis and development of hepatocellular carcinoma (HCC) induced by chemical substances in rat model. Methods Fifty male and 50 female Sprague-Dawley rats (age of 5-6 weeks) were equally divided into four groups: male experimental (surgical castration) and control groups and female experimental (surgical castration)and control groups. The HCC model was induced by diethylnitrosamine (DEN) and Nnitrosomorpholine (NMOR) in SD rats. The effects of gonadectomy on occurring and development of HCC were observed. Results The incidence of HCC in female experimental group was higher than that in female control group (11/11 vs 5/14, P=0. 001), while it was lower in male experimental group than that in male control group (3/10 vs 12/12, P=0. 001). It was demonstrated that gonadectomy could increase the growth of HCC (P=0. 013) and tumor metastasis (P=0. 036) in female rats, but not in male rats. The formation of liver cirrhosis and HCC was found at 8 and 16 weeks in male experimental group, at 12 and 20 weeks in male control group, at 16 and 20 weeks in female experimental group and at 12 and 16 weeks in female control group. These findings showed that gonadectomy could improve the development of carcinogenesis in female rats and delay the carcinogenesis in male rats. Conclusion Sex hormones, especially estrogens, may be involved in development and metastasis of rats HCC. Key words: Carcinoma, hepatocellular;  Castration;  Ovariectomy;  Gonadal steroid hormones; Disease models, animal