Which Family History Can Affect Colorectal Cancer Risk?
A first-degree relative is a parent, sibling or child. Having colorectal cancer in a first-degree relative may be more relevant to your personal risk than having the disease in a more distant relative, such as an aunt, uncle or grandparent.
Family history may be particularly relevant when:
- A parent, sibling or child has had colorectal cancer
- More than one first-degree relative has been diagnosed
- A relative developed colorectal cancer at a relatively young age
- Several relatives across generations have had colorectal or certain other cancers
- There is a known hereditary colorectal cancer syndrome in the family
These factors should be considered together rather than individually. A doctor can review your family history alongside other relevant risk factors to determine whether you may need earlier or more frequent screening or evaluation for a hereditary cancer syndrome.
Does a Family History Mean Colorectal Cancer Is Hereditary?
Hereditary colorectal cancer syndromes are different. They involve inherited genetic changes that can increase a person's likelihood of developing colorectal cancer and, depending on the syndrome, certain other cancers.
A doctor may therefore look beyond whether one relative has had colorectal cancer and consider the broader pattern of colorectal and other cancers within the family.
When Might an Inherited Cancer Syndrome Be Suspected?
A doctor may suspect an inherited cancer syndrome if your personal and family cancer history suggests that a genetic change could be contributing to your risk.
Two recognised hereditary conditions associated with colorectal cancer are Lynch syndrome and familial adenomatous polyposis (FAP). These conditions have different genetic causes and patterns of cancer risk, so assessment and surveillance recommendations can differ.
A family pattern suggestive of hereditary cancer does not confirm that a genetic condition is present. Depending on your history, a healthcare professional may discuss whether genetic counselling or testing should be considered.
How Can Family History Influence Screening Decisions?
For people at average risk, colorectal cancer screening generally follows age-based recommendations. A significant family history, however, may mean that screening should begin earlier or take place more frequently.
Singapore guidance distinguishes between different levels of familial risk. For example, where a first-degree relative developed colorectal cancer at age 60 or younger, or where two or more first-degree relatives have been affected, colonoscopy may be recommended from age 40 or 10 years before the youngest diagnosis in the family, whichever comes first. Screening recommendations may differ for other family-history patterns.
People with certain hereditary colorectal cancer syndromes may require a substantially different surveillance schedule.
Because these recommendations depend on your family and medical history, it is useful to discuss your circumstances with a specialist rather than deciding when to screen based on age alone.
Understand Your Colorectal Cancer Risk at The Surgeons
If colorectal cancer runs in your family, speaking with a doctor can help you understand how this may affect your own risk and screening needs. Where the family pattern raises concern about an inherited risk, a hereditary cancer syndrome may also need to be considered.
At The Surgeons, Dr Chew Min Hoe, medical director and senior consultant general and colorectal surgeon, has more than 25 years of experience in colorectal care. Book an appointment with us to discuss whether your family history changes your colorectal cancer risk or the screening recommended for you.
Frequently Asked Questions About Family History and Colorectal Cancer
Meet Our Doctor
Dr Chew Min HoeSenior ConsultantGeneral & Colorectal SurgeryMBBS (Singapore), MRCS (Edinburgh), MMed (Surgery), FRCS (Edinburgh)
Dr Chew Min Hoe is a colorectal surgeon with more than 25 years of experience in colonoscopy and colorectal surgery. His background includes senior surgical leadership roles in Singapore’s public healthcare sector, a fellowship at Royal Prince Alfred Hospital in Australia and more than 100 peer-reviewed publications.
