All the individual factors that increase a person’s chances of developing a particular disease, such as cancer, are generally referred to as risk factors for the disease. There are different risk factors for different cancers. For example, unprotected exposure to strong sunlight is a risk factor for skin cancer and smoking is considered to be one of the most important risk factors for lung cancer.
The risk factors for colorectal cancer are not yet well known, but both environmental factors and heredity are considered to have an effect on tumor growth. Here are some factors that are believed to have an effect on the likelihood of illness.
- age (cancer risk increases after 50 years of age)
- low-fiber diet rich in animal fat and protein
- being overweight
- lack of exercise
- long-term inflammatory bowel disease such as ulcerative colitis or Crohn’s disease
- previous digestive polyps
- previous colon or rectal cancer
- family history of colorectal cancer
In 2018, the World Cancer Research Foundation published a report on the impact of food, exercise and other lifestyles on various cancers. According to research, exercise, whole grains, fiber and dairy products reduce the risk of developing bowel cancer. You can read more about the report on their website: How diet, nutrition, and physical activity affect colorectal cancer risk
Susceptibility to colorectal cancer may be inherited. About 5 percent of colorectal cancers are hereditary. The most common reason for this is Lynch syndrome, which predisposes its carriers to different cancer types. Lynch syndrome is also known as hereditary non-polyposis colorectal cancer (HNPCC).
Lynch syndrome is a gene defect that has a 50% probability of being inherited from the carrier of the mutation to his child. Lynch syndrome is particularly prone to cancer of the colon, but also to cancers of the uterus, stomach, urinary tract, ovary, small intestine, breast and bile. Depending on the gene, carriers of the mutation have a risk of 15-46% for colon cancer, 43-57% for uterine cancer, and 10-17% for ovarian cancer by age 75.
It is estimated that there are more than 10,000 people with Lynch syndrome in Finland. Some common signs for Lynch syndrome are:
- Developing colorectal or endometrial cancer younger than age 50.
- Close family members (parents, siblings, children) are diagnosed with Lynch cancer at ages that are younger than the average for their type of cancer.
The only known method of accurately diagnosing Lynch syndrome is through genetic testing. If the family is known to have Lynch syndrome, it is recommended that family members have regular screening tests. With screening many diseases are found in the early stages.
Long-term inflammatory bowel diseases such as ulcerative colitis and Crohn’s disease increase the risk of colorectal cancer. People with these diseases are advised to have an annual colonoscopy, as the disease has continued for a long time.
Also, individuals suffering from a rare genetic disease in which the large intestine polyps develop hundreds of young age (e.g. familial adenomatous polyposis, Peutz-Jeghers polyposis or juvenile polyposis), there is a considerable risk of developing colon cancer. For them, regular colonoscopies and complete polyps removal are necessary.