Hereditary Colorectal Cancer
While the majority (50-60%) of colorectal cancers are sporadic (occurring in individuals without a family history of colorectal cancer), colon cancer can also be familial (30-40%) or associated with a specific genetic abnormality (inherited colorectal cancer syndromes – 4-6%).
Sporadic colorectal cancer occurs due to a series of random mutations that are not passed down to the next generation.
In familial colorectal cancer, individuals with a first-degree relative (parent, sibling, child) with colorectal cancer may have a predisposition to getting colorectal cancer. Such patients should have a screening colonoscopy performed at the age of 40 (or 10 years before the youngest affected relative), and repeated every 5 years.
Hereditary colorectal cancer is associated with a specific genetic abnormality. In these cancer syndromes, a specific gene has been identified that is responsible for the development of colorectal cancer in affected families. Some cancer syndromes may also increase the risk of non-colorectal cancers such as cancer of the duodenum (first portion of the small intestine), female reproductive organs, and others. As genetic researchers continue to identify and define certain syndromes, more genes that predispose to colorectal cancer are likely to be identified.
Some of the hereditary cancer syndromes we are aware of now include:
- HNPCC (Hereditary non-polyposis colorectal cancer; Lynch syndrome)
- FAP (Familial adenomatous polyposis)
- aFAP (Attenuated FAP)
- APC 1307K
- Peutz-Jegher’s syndrome
- MAP (MYH associated polyposis)
- Juvenile polyposis
How can my family be tested for hereditary cancer?
Genetic counselors can help quantify your family’s risk of a hereditary cancer syndrome. Genetic testing may be performed through an oral swab or simple blood tests. For a more thorough evaluation of your specific condition and to see if genetic counseling or testing is recommended for your family, call to schedule an appointment for a consultation with Dr. Zaghiyan.
When should families with hereditary cancer be screened?
Screening recommendations for families with hereditary cancer syndromes differ according to the type of hereditary cancer affecting your family. In some cases, screening may be recommended starting at a very young age (teens or 20s). For more information regarding screening recommendations or genetic testing for your family, make an appointment to discuss your condition with Dr. Zaghiyan in her office in Los Angeles.