Some of the causes and risk factors for colon cancer, such as family history of the disease, are beyond your control. But a surprising number of them are.
Scientists are still trying to understand why healthy cells in the colon and rectum become cancerous, grow and spread out of control. But researchers know that colorectal cancer is the result of damage to a cell’s DNA, resulting in genetic changes called mutations.
A small percentage of mutations capable of causing colorectal cancer are hereditary, i.e. passed down in families. Most, however, are acquired, meaning they develop over a person’s lifetime, usually due to environmental or lifestyle factors. For the majority of people who develop colorectal cancer, there is no single genetic pathway to the disease. Scientists are working to better understand the complex interplay of factors that cause this cancer.
Hereditary causes of colon cancer
A small number of people inherit genetic mutations from their family that significantly increase their risk of colorectal cancer. They usually develop certain syndromes (sets of symptoms) linked to this genetic inheritance.
Familial adenomatous polyposis ( FAP), attenuated FAP (AFAP) and Gardner’s syndrome
These conditions are directly linked to the inheritance of a mutated APC gene. When functioning properly, APC acts as a brake on cell growth. When mutated, it is part of a biochemical chain reaction that leads to the formation of hundreds of polyps in the colon, which can become cancerous.
Lynch syndrome (hereditary non-polyposis colon cancer)
This is an inherited cancer syndrome that increases the risk of many cancers, including colorectal cancer. Mutations usually occur in the MLH1, MSH2, MSH6, PMS2 or EPCAM genes. These genes are involved in DNA repair. When mutated, they are unable to prevent mutations that can lead to cancer.
Mutations in the STK gene (also called LKB1) are at the cause of most cases of this syndrome. When not mutated, this gene prevents cells from growing rapidly and uncontrollably. The uncontrolled growth, in this case, leads to colorectal polyps which can become cancerous.
Risk factors for colon cancer that you cannot control
Some risk factors for colon cancer are beyond your control. This list includes:
Although an increasing number of people are being diagnosed with early stage colorectal cancer early, the majority of people with the disease are over 29 years old.
– Personal or family history
If you have had colorectal polyps (abnormal growths in the colon or rectum), you are more likely to develop colorectal cancer. This is especially true if the polyps are large, multiple, or contain cells with non-cancerous abnormalities (dysplasia).
– A family history of colorectal cancer is another risk factor. One in three people diagnosed with colon or rectal cancer have family members with the disease.
– Having had colorectal cancer increases the risk of recurrence , even if you were treated successfully the first time.
– A personal history of inflammatory bowel disease (IBD)
Inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis, causes chronic inflammation of the colon. This can lead to dysplasia, which can eventually become cancer.
– Type 2 diabetes
People with this form Non-insulin-dependent diabetes mellitus not only have a higher risk of colon cancer and rectal cancer, but also tend to have a poorer prognosis after diagnosis.
risk under your control
There are certain risk factors for colorectal cancer that you can change (at least in theory). These include:
Men and women who are overweight or obese face a increased risk of colorectal cancer. Men, especially those who accumulate extra pounds around the waist, are the most vulnerable.
Rising rates of colorectal cancer in young people could also be due to the increase obesity rates. A study published in JAMA Oncology in 800 followed the health of over 85 000 women during 22 years and revealed that the higher a woman’s body mass index (BMI), the greater the risk of developing colorectal cancer before 50 years is important.
The study found that women aged 18 to 49 years who were considered overweight or obese had up to twice the risk of developing early-onset colorectal cancer than women who reported the lowest BMIs.
There is a strong body of evidence linking lifestyle sedentary to an increased risk of colorectal cancer and rectal cancer. A meta-analysis of 29 studies, published in the journal Medicine in 2017, revealed a statistically significant association between daily sedentary time, more specifically, watching television, and the risk of colorectal cancer.
The study also found that people who had jobs that required prolonged sitting were more likely to develop colorectal cancer.
Researchers found that every two hours increase in daily TV time increased the risk of colorectal cancer by 7%; two additional hours of work-related sitting resulted in a 4% increase.
A diet rich in meat
A diet rich in in red meat and processed meat has been associated with an increased risk of colorectal cancer. IARC, the cancer control agency of the World Health Organization, has gone so far as to call processed meat a carcinogen and red meat a probable carcinogen. Twenty-two experts from ten countries reviewed over 800 studies to reach these conclusions. They found that the daily consumption of 29 grams of processed meat, the equivalent of about four slices of bacon or of a hot dog, increased the risk of colorectal cancer by 18%.
Alcohol and tobacco
Researchers have established a link between moderate or heavy alcohol consumption and an increased risk of colon cancer and of the rectum. The evidence for this link is generally stronger in men than in women, but studies have found a link for both sexes.
Smoking Most people know that smoking increases the risk of lung cancer, but it is less well known that it also increases the risk of colorectal cancer.
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