Colon cancer is one of the most common cancers worldwide. The chances of developing this disease are around 6.5%. This disease sometimes runs in families and around 35% of cases are hereditary and linked to a certain genetic disorder.
Due to its high prevalence, screening tests such as colonoscopy or stool tests are recommended. Early detection of colon cancer saves lives and allows effective treatment.
There are several known types of colorectal cancer. Genetic counselling is recommended in cases of a family history, polyps found during colonoscopy, or recurrent tumors after treatment.
Hereditary colon cancer
There are several types of hereditary colon cancer syndromes that can be clinically diagnosed through genetic testing:
FAP (familial adenomatous polyposis) is a condition that causes polyps to grow in the colon. Patients with FAP suffer from hundreds, if not thousands, of precancerous polyps that become malignant within several years if left untreated. Considering the high risk of developing colon cancer in these cases, healthcare providers recommend intensive medical follow-up or colon removal surgery.
For this reason, when one of the parents suffers from this disorder, it is important to detect the genetic mutation and offer suitable treatment for them and their children.
Lynch syndrome (HNPCC)
Lynch syndrome, also known as HNPCC (Hereditary nonpolyposis colon cancer) creates a risk of up to 80% for developing colon cancer before age 70. Tumors in these cases are extremely stubborn and can reappear even after a colon removal, in other areas.
Besides colon cancer, people with Lynch syndrome are also at an increased risk for endometrial, urinary tract, ovarian, breast, skin, and bile duct cancer.
The diagnostic criteria for HNPCC are also known as Amsterdam criteria. Criteria includes at least three family members with colorectal or endometrial cancer, cancer that extends at least two generations, a diagnosis before age fifty, and FAP excluded via colonoscopy.
Diagnosis of lynch disorder is almost always given using the Amsterdam criteria, and not by genetic screening tests.
Colorectal cancer can also occur as part of other disorders that include a genetic tendency for tumors in various organs.
In many cases, these disorders are difficult to diagnose. For this reason, people suffering from colorectal cancer tend to develop tumors in other body areas and should be in constant oncological follow-up.
Who is at risk for hereditary colon cancer?
Like other types of cancer, colorectal cancer is suspected to be hereditary when tumors occur at an early age (before 50), in cases of recurring cancer, or when many polyps are diagnosed during colonoscopy.
In addition, a family history of colorectal cancer or other malignant diseases (such as ovarian, kidney, or endometrial cancer) is a risk factor for this disease. In these cases, genetic counselling can help patients receive up-to-date information and make important decisions concerning treatment.