Is Colon Cancer Genetic?

According to colon cancer statistics, colon cancer is the third leading cause of death in the United States. But colon cancer can be prevented. One way to prevent colon cancer is through colonoscopy screenings. And colonoscopies are recommended starting at age 50 or 10 years younger than your age if you have a family history of colon cancer and polyps.

Suppose you develop colon cancer without any family history. However, there has been some research recently that suggests genetics may play a role in developing certain types of colon cancers and precursors. “Almost 90 percent of colon cancers and adenomas (colorectal polyps) occur sporadically,” according to “Understanding Genetics.

Genetic colon cancer

Family history is one of the risk factors. Suppose colon cancer or colon polyps run in your family. In that case, it doesn’t necessarily matter how old you are when diagnosed

According to Genetics Home Reference, the genetic mutations that cause colon polyps and  cancers to form aren’t passed down through families; they usually occur spontaneously during normal cell division. And these gene changes don’t always happen in every family member that has a history of colon polyps or cancer. Because not all people who have a family history of these conditions get them, there must be factors involved in developing this condition that is still unknown.

Some develop from colon polyps caused by hereditary issues. People who have inherited  cancer syndromes may be at risk of colon polyps and colon cancer even if there is no family history of these conditions. According to Genetics Home Reference, some people inherit colon cancer susceptibility genes that make them more likely to develop colorectal tumors.

This condition is called familial adenomatous polyposis (FAP), and it’s associated with an increased risk for cancer. According to “Understanding Genetics: Cancer,” FAP occurs when a person inherits one copy of the defective APC gene from each parent; people with two copies of this gene typically develop multiple benign colorectal adenomas.

According to Genetics Home Reference, people with Lynch Syndrome (LS) are also at risk for colon polyps and cancers. This condition is caused by an inherited mutation in several DNA mismatch repair genes, which prevents the body from correcting errors when it replicates cell divisions.

Chronic inflammation has been associated with precursors like colon dysplasia, but inflammatory bowel disease (IBD) doesn’t cause cancer on its own. Apart from that, there’s no evidence that diet or environmental factors play a role in causing colorectal tumors to form; nor is there any proof that colitis causes changes in colon cells that lead to cancer.

Colon cancer tests

Since colon polyps and colon cancers seem to develop spontaneously, there’s no test for them – and it’s not possible to find it before symptoms appear. But colonoscopy is the only screening recommended by the American Cancer Society; colonoscopies can detect colon polyps and colorectal tumors during the early stages of development when they’re most likely to be curable.

There is a greater risk of developing cancers in people who have FAP or LS. And some forms of Lynch Syndrome increase the risk for colorectal tumors even if a person doesn’t have any family history. A few individuals with LS develop colon polyps and colon cancers, but not all these people eventually get cancer.

Lynch Syndrome typically affects the colon and rectum in adults over age 50. The colon is often involved with colorectal tumors that begin as colon polyps.

They can also occur within endometrial (uterine) and ovarian tissue areas in women affected by LS. And some Lynch Syndrome patients have been found to have an increased risk for mid-gut carcinoids, which are rare tumors of the small intestine. However, other forms of colon polyps and colon cancers don’t appear to be genetically linked to colon cancer syndromes.

In addition, colon cancer in LS colon cancer patients may be due to a mutation called mismatch repair-deficient colon cancer, according to Genetics Home Reference. In this condition, colon cancers develop from cells with abnormal chromosomes.

So it’s not known if colon polyps and colon cancers associated with Lynch Syndrome are inherited or arise spontaneously in the affected tissue – leading some experts to believe that they’re always caused by spontaneous cell changes rather than inherited gene defects. This lack of information about Lynch Syndrome, in general, weakens the genetic cause in individual cases of colon tumors in people who have LS.