Symptoms of colorectal cancer 
Colorectal cancer is usually unnoticed in its early stages of growth. The following symptoms may indicate cancer colorectal.
* Changes in fecal habits alternating between constipation and diarrhea.
* Blood in the stool.
* A permanent discomfort in the stomach: cramps, gas or pain.
* The feeling that the bowel does not empty completely or having constant desire to defecate.
* A large fatigue.
* An unexplained weight loss.
Note. The presence of blood in the stool may be another explanation, such as hemorrhoids or anal fissure. In addition, some foods can color the stool. This is the case of beets and red licorice.
People at risk
* Age. The disease mainly affects people over 50 years (90% of cases).
* Personal or family history. The risk increases when they have already suffered from colorectal cancer or polyps or a family member has suffered. This predisposition is not always hereditary origin. It may be the result of exposure to a carcinogen in the environment or eating habits or lifestyle. Some genetic diseases of the colon increase the risk of colon cancer. The two most common forms are hereditary colorectal cancer without polyposis (or Lynch syndrome) accounts for approximately 5% of cases of colorectal cancer and adenomatous polyposis family, involved in about 1% of cases. The latter is manifested by the appearance of a large number of polyps, as a teenager.
* Sex. Men are slightly more at risk than women.
* Inflammatory bowel disease. Being affected by Crohn’s disease or ulcerative colitis increases the risk.
* Diabetes. In epidemiological studies, it was found that colorectal cancer is more common among individuals with type 2 diabetes than among those not reached.
Risk Factors
* Smoking. Especially those who have smoked for many years. See our Smoking sheet.
* The consumption of alcohol. Research has shown a link between alcohol consumption (even when it is moderate) and several types of cancers: breast, colon and rectum, esophagus, larynx, liver, mouth and pharynx2, 3. The more alcohol consumed, the greater the risk of cancer rises, regardless of the type of alcohol (wine, beer or spirits). It appears that alcohol-related harm are partially countered by an adequate consumption of foods containing vitamin B9 (folate).
* Obesity and overweight. Consequence of physical inactivity and poor diet, excess weight would be a major risk factor for several cancers, including esophagus, colon, breast, endometrial and rein4. See our Obesity sheet.
* Physical inactivity. In addition to causing overweight, physical inactivity would prevent the proper operation of certain mechanisms needed to maintain health. Physical fitness reduces the risk of colon cancer and cancer sein4.
* A diet rich in red meat in sausages (salami, sausages, smoked ham, etc.). Aubarbecue and grills, and low in fruits and vegetables.
* The lack of natural light. It appears that the risk of colon cancer are higher in regions of the world where people are less exposed to natural light. It is believed that the protective effect is due to the mechanism by which the sun causes the production of vitamin D. We must, of course, protect skin with sunscreen adequate.
Psychological factors
The role of the psychological state in the development of cancer is controversial. Some personality traits have been associated in studies with an increased risk of cancer. Other studies, however came to contradict this hypothesis. To learn more, read our information sheet Cancer.