IGF1 and colorectal cancer: In a study which was done to compare women with colorectal cancer who were taking estrogen with women not taking estrogen, the results showed that the estrogen has no role in the etiology of colorectal cancer but women who took the estrogen had more advanced disease when compared to the other group, the reason behind this is not clearly understood but this effect may be explained by the effect of estrogen of the bile acid concentration, estrogen mediated changes on the intestinal epithelium, and the changes of the levels of the insulin and insulin-like growth factor I [28,33].