Epidemiological studies have reported that vitamin D deficiency is associated with increased risk of morbidity and mortality for many diseases, including tumors and inflammatory diseases.
Indoleamine 2,3-dioxygenase (IDO) involvement has been observed in several cancers and has been mainly associated with negative prognostic factors and worse outcome.
Moreover, smoking is a well-known risk factor for almost all cancers and their pre-malignant precursors, as well as for inflammation. However, few studies have investigated the effect of vitamin D insufficiency, IDO activity (expressed as kynurenine/tryptophan ratio) and smoking on colorectal polyps. This study aims to investigate the effects, and possible interactions, of vitamin D, IDO activity and smoking in people undergoing complete colonoscopy. According to the results that will be obtained, screening for CRC through colonoscopy might constitute an opportunity to also 1) assess vitamin D status and eventually prevent ipovitaminosis; 2) evaluate smoking habits and promoting the quitting; 3) measuring IDO activity and shed some light into its possible additional implications as a biomarker of peripheral immune tolerance or prognosis.
