Correlation between gender and spontaneous C-cell tumors in the thyroid gland of the Wistar rat

In many rat strains, C-cell hyperplasia occurs in an age-dependent manner a nd is often associated with multifocal C-cell carcinoma. The purpose of thi s study was to investigate the spectrum of spontaneous, proliferative C-cel l disorders by gender in Wistar rats throughout their lifespan. The inciden ce of C-cell hyperplasia shows a significant increase with age (P<0.001) an d is much higher in female rats than in male rats (P<0.05). From 3 to 24 mo nths of life, 27.5% of female rats showed a normal C-cell pattern, 55.0% sh owed C-cell hyperplasia, and 17.5% showed C-cell tumors; while 57.5% of mal e rats showed a normal C-cell pattern, 32.5% showed C-cell hyperplasia, and 10% showed C-cell rumors. Although the overall frequency of C-cell neoplas ms in females was nearly double that in males, these data are not statistic ally significant. However, the number of C-cell tumors showed a significant increase with age (P<0.05). Therefore, we can conclude that there were sig nificant differences in the incidence of the total spectrum of C-cell proli ferative abnormalities in the thyroid gland of Wistar rats that were both a ge-dependent and gender-dependent.