Some of these indicate the carcinogenic properties of testosterone, dihydrotestosterone (DHT), growth hormone and insulin‑like growth factor (IGF) and others, demonstrating their neutral nature or even their protective one, as in the case of vitamin D. Thus, the synergistic nature of anabolic substances with other CRC risk factors (such as type 2 diabetes mellitus, metabolic syndrome and smoking) has emerged, suggesting a more holistic approach.
Among nonsmokers or nondrinkers, individuals who had the GH1 A/A genotype were at a decreased risk of developing colorectal cancer compared with individuals who had the GH1 T allele.
A common polymorphism in the GH1 gene, rs2665802, was previously shown to be associated with lower IGF-I levels and decreased colorectal cancer (CRC) risk.
The present study thereby demonstrates a central role for the GH/IGF system in the pathogenesis of some colorectal cancers and suggests that specific GHR blockade may present a new concept in the treatment of colorectal cancer.
Our data demonstrate that GHR is frequently expressed in human CRCs and appears to be up-regulated compared to normal mucous tissue, thus supporting a possible role for growth hormone in CRC physiology.
The human T1663AGH1 gene polymorphism, which may confer lower levels of GH and IGF-I, appears to be associated with a decreased risk of colorectal cancer.