Current Tissue Molecular Markers in Colorectal Cancer: A Literature Review

Table 1

Environmental risk factors.

Environmental factors
Age	The risk of developing CRC increases with age and the majority of the cases are diagnosed in patients older than 50 years [8–10]. A higher prevalence is reported in people aged over 60 years compared to those younger than 40 years [2].
Gender	In the literature the incidence of CRC is the same in males and females. Females are shown to be older and to have right-sided tumors and less advanced diseases [11].
Westernized lifestyle	Long-term smoking is strongly associated with the development of adenomatous polyps and is important for both formation and aggressiveness [12]. Recent meta-analyses point out a statistically significant increase of risk after 30 years of smoking, especially in CRCs displaying MSI. A greater association with rectal and proximal colon tumors is also reported [13, 14].
	Diet is surely one of the most important risk factors, especially one rich in red meat. This association between red meat and cancer, stronger for the colon cancer, may depend on the presence of heme iron in meat [15–17].
	Alcohol consumption also is a known risk factor for CRC. The interference on the folate synthesis, with the production of acetaldehyde that degrades folate, may be at the basis of the chromosome damage and so of the carcinogenesis process [18, 19].