Colorectal cancers are favoured by the coexistence of several risk factors in the same person. The most important risk factors are modifiable, in particular those linked to diet and lifestyle, whereas risk factors linked to age, genetics and heredity are unfortunately not modifiable.
- Age :
In both men and women, the risk of the disease begins to rise from the age of 50.
And as age advances, the risk of colorectal cancer increases. In Algeria, 5% of colorectal cancers occur before the age of 50. .
- Overweight and obesity
The presence of abdominal fat (in the belly) increases the risk of colorectal cancer more than a high Body Mass Index.
- Sedentary lifestyles and physical activity
Light activity already reduces the risk of colon cancer, while regular, intense physical activity can reduce the risk by as much as 40-50% compared with sedentary people.
- Diet 
The scientific knowledge acquired on the predominant role of diet in colorectal cancer has made it possible to determine how diet can increase or decrease the risk of this cancer.
- Consumption of red meat (particularly beef), processed meats (salted, smoked, etc.) and cold cuts increases the risk of colorectal cancer.
- The higher the calorie content, the higher the fat content and the lower the fiber content of a diet, the greater the risk of colorectal cancer.
- The fiber contained in wholegrain cereals reduces the risk of colorectal cancer, as do dairy products, due to the calcium they contain.
- Fresh (non-starchy) vegetables and fruit, fish, foods containing vitamin C and foods containing vitamin D (oily fish, mushrooms, milk, etc.) are beneficial.
- Alcohol consumption increases the risk of colorectal cancer
- Alcohol consumption increases the risk of colorectal cancer. Wine, beer and strong spirits are equally concerned.
- Smoking moderately increases the risk of colorectal cancer, particularly rectal cancer. This risk is proportional to the duration of exposure and the number of cigarettes smoked per day.
- Exposure to asbestos
- Prolonged exposure to asbestos in the workplace over many years is associated with the occurrence of colorectal cancer, particularly colon cancer. 
- Heredity and genetics
- Colorectal cancer occurs in a predisposed family background in 15% of cases.
- The occurrence of colorectal cancer in one or more first-degree relatives (father, mother, brother or sister) before the age of 50 increases the risk.
- A genetic mutation is linked to 5% of colorectal cancer cases. There are 02 forms:
- Familial adenomatous polyposis, linked to the mutation of genes (APC, MUYTH) responsible for the appearance of hundreds or even thousands of colorectal polyps in adulthood. If these polyps remain untreated, the risk of colorectal cancer rises to 100%.
- Lynch syndrome, or hereditary colon cancer without polyposis, is characterized by gene abnormalities. These people have an 80% risk of colorectal cancer.
- Pre-disposing diseases
Severe chronic inflammatory bowel disease (IBD) of more than 10 years’ duration, such as Crohn’s disease and ulcerative colitis, increases the risk of colorectal cancer. These people often benefit from individual follow-up
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