Is colorectal cancer hereditary?

Colorectal cancer can affect any part of the large intestine (colon) and rectum. Most colorectal cancers develop on the inner wall of the colon and rectum and usually begin with tumors called polyps.
These polyps are benign and usually harmless tumors, however they can become cancerous if left undetected.
Colorectal cancer may also be called colon cancer or rectal cancer, depending on the location of the cancer and the area from which it originates.
1 in 18 people (5.5%) will get colon cancer in their lifetime. Of all colon cancer cases, only about 5 to 10 percent are hereditary, involving genetic mutations inherited from the mother or father.
Many genes are associated with hereditary colon cancer, but mutations in the genes associated with Lynch syndrome (MLH1, MSH2, MSH6, PMS2, EPCAM) are the most common cause of the inherited form of the disease. colorectal cancer. Predictive models can estimate an individual's risk of Lynch syndrome mutations.
About 25 to 35 percent of colorectal cancers are familial, meaning the disease occurs in family members more often than is expected in the general population, although a specific gene mutation has not been identified in the family. With colorectal cancer in families, the specific cause of colorectal cancer is unknown but it is possible that a combination of risk factors including genetics, lifestyle, and environment increase the risk. body in the family.
Screening recommendations vary for individuals with an increased lifetime risk of colorectal cancer based on inherited cancer syndromes or family history.
The remainder of colorectal cancer diagnoses (approximately 70%) are considered incidental or sporadic and non-hereditary, with no identifiable etiology. Risk factors for non-inherited colorectal cancer include:
Age (9 out of 10 people over 50) Inflammatory bowel disease, ulcerative colitis, Crohn's disease Diets high in fat and/or low fiber Smoking/use of tobacco products Physical inactivity and/or obesity Type 2 diabetes

One of the risk factors for colorectal cancer is having a family history of the disease. Colorectal cancer is called hereditary cancer when several generations of a family have the disease.
Experts have found changes in genes (also known as mutations or abnormalities) that cause colorectal cancer. A gene is a block of DNA that holds the genetic code or instructions for making proteins important for our bodily functions.
Children of people carrying these genes have a 50% chance of getting it from their parents.
The two most common hereditary colorectal cancer syndromes are hereditary non-polyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP). These two types account for less than 5% of all colorectal cancers.

Hereditary non-polyposis colon cancer (Lynch syndrome)
Hereditary non-polyposis colorectal cancer also known as Lynch syndrome, is the most common inherited form of colon cancer, accounting for about 3% the total number of colorectal cancer diagnoses per year. People with HNPCC usually have at least three family members and two generations with colorectal cancer and cancers that develop before age 50.
Although not everyone who inherits the HNPCC gene will get colorectal cancer, the risk is very high: about 80%. People with HNPCC also have an increased risk of other cancers associated with Lynch syndrome, such as cancers of the kidney, ovary, uterus, pelvis, small intestine, and stomach.
Doctors can check colorectal cancer patterns in relatives to see if the family has HNPCC. The "HNPCC family" must have certain markers of a pattern of colon cancer across generations. These are called Amsterdam Criteria (Amsterdam Criteria) and include:
At least three members of the family with cancer related to Lynch syndrome At least two successive generations with this type of cancer Two family members with cancer the disease is a first-degree relative (i.e. parent, sibling, or child) of another family member with Lynch syndrome cancer At least one member had colorectal cancer at age 50 age or earlier Check with your doctor if you think these criteria run in your family. Colonoscopy is recommended for family members 10 years younger than the youngest family member diagnosed with cancer. You should also be screened for other cancers associated with Lynch syndrome. For people diagnosed with Lynch syndrome, screening usually begins between the ages of 20 and 25.
Familial adenomatous polyposis (FAP)
Familial adenomatous polyposis (FAP) is a rare condition marked by the presence of hundreds or thousands of benign, noncancerous polyps in the large intestine and upper respiratory tract. It is thought to occur in about 1% of all people diagnosed with colorectal cancer each year.
The polyps start early, with 95% of people with FAP having it by age 35, and are often also found in teenage patients, with 50% having polyps by age 15. Polyps will become cancer, usually by age 40. Thyroid cancer is also associated with FAP.
Although most cases of FAP are genetic, almost a third are the result of spontaneous (newly occurring) gene changes. For those who develop the new gene mutation, they can pass the FAP gene on to their children.
Genes are small pieces of DNA that control how a cell works, such as telling the cell when to divide and grow. One copy of each gene comes from your mother; the other comes from your dad.
In 1991, researchers identified a gene called APC that is responsible for FAP. This gene can be found in 82% of FAP patients. The lifetime risk of colon cancer in people with this gene change is close to 100%.

What is the difference between FAP and HNPCC?
The two main differences between FAP and HNPCC are:
Number of genes involved. In FAP, only one gene, APC, is mutated. In HNPCC, certain genes are altered that can cause the condition. Presence of polyps. FAP is marked by the presence of more than 100 benign polyps. People with HNPCC have fewer polyps, but they can become cancerous faster than normal. Other forms of hereditary polyposis
Other hereditary polyposis syndromes are associated with a higher risk of colorectal cancer, including:
Juvenile polyposis. Patients can have between 5 and 500 polyps, mainly in the colon and rectum. They usually occur before the age of 10. The stomach and small intestine can also be affected. People with this condition are also more likely to develop bowel cancer. Peutz-Jeghers syndrome (PJS). People with PJS often have tens to thousands of benign polyps in the stomach and intestines, mostly in the small intestine. Tumors may become malignant or may cause intestinal obstruction.

Blood tests can find changes in genes that make some people more likely to have FAP or HNPCC.
You may consider genetic testing and counseling if:
You have had more than 10 colon polyps You have had colon polyps and other types of tumors You are of Ashkenazi Jewish descent and your family has money history of colon cancer or polyps If you test positive for the changes in the genes mentioned above, your doctor will likely recommend an annual colonoscopy. This is a diagnostic technique that checks your colon for cancer or polyps. If you already have colon cancer or polyps, your doctor can talk to you about resection, which is surgery to remove your colon. Your loved one may also consider genetic counseling and testing. Vinmec International General Hospital is implementing a package of screening and early detection of colorectal cancer, implemented by a team of experienced doctors and doctors in the field of colorectal cancer diagnosis and treatment. , with the support of a system of modern technological equipment and facilities, full of specialized means to diagnose the disease and classify the pre-treatment stages such as: Endoscopy, CT scan, PET-CT scan, MRI , Mammography, histopathological diagnosis, gene-cell testing,... help detect colon cancer early even when there are no symptoms.
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Reference source: iconcancercentre.sg, webmd.com