Genetic testing for colorectal cancer
If you have a history of colorectal cancer in your family, we recommend a genetic test to see if you are at risk for the disease.
Statistically, colorectal cancer affects one in 20 people. About 25% have a family history of recurrent cases of the disease. However, in addition to hereditary predisposition, the influence of many other factors besides genetics cannot be discounted. And only 5% of all cases can be considered directly hereditary.
Lynch syndrome is considered a hereditary nonpolyposis colon cancer. And it accounts for the majority of genetically determined colorectal cancer cases (2-3% of all cases).
Who is recommended to have a genetic test for colorectal cancer?
A person whose family history suggests a predisposition to the development of genetically determined colorectal cancer. These factors include :
A family history of early onset :
- Colorectal or endometrial cancer before the age of 50
- Colorectal cancer before the age of 60 and high frequency microsatellite instability on histological analysis
Multiple polyps in the colon :
- Colorectal adenomatous polyps (if more than 10)
- Gamartoma gastrointestinal polyposis
Family history :
- Patient whose close family members include several people with colorectal cancer or Lynch Syndrome.
Benefits of genetic tests to reduce risk:
Determining the right strategy to control or even manage the disease is possible. First, we need to obtain reliable clinical data, namely to determine the presence of a pathogenic mutation to link the clinical phenotype to a specific type of genetically determined colorectal cancer or associated syndrome.
Management options include:
For Lynch Syndrome
Surveillance
- Colon & rectum: Colonoscopy every 1-2 year(s), starting at age 20-25
- Endometrium & ovary: Gynecologic cancer screening
- Others:
› Esophagogastroduodenoscopy (EGD) including side-viewing examination every 1-2 year(s), starting at age 30-35
› Annual urinalysis starting at age 30-35
› Annual physical exam including screening for skin cancers
Prophylactic Surgical Options
- Prophylactic colectomy in young CRC patients
- Prophylactic hysterectomy and/or bilateral salpingo-oophorectomy, after childbearing is completed
For Familial Adenomatous Polyposis (FAP)
Surveillance
- Colon & rectum: Colonoscopy every 1-2 year(s), starting at age 10-12
- Others:
› EGD including side-viewing examination every 1-3 years, starting when colorectal polyposis is diagnosed or at age 20-25
› Annual physical exam including cervical ultrasonography, starting at age 25-30
Prophylactic Surgical Options
- Prophylactic colectomy when polyps become unmanageable
For attenuated Familial Adenomatous Polyposis (aFAP)
Surveillance
- Colon & rectum: Colonoscopy every 2 years, starting at age 18-20
- Others:
› EGD including side-viewing examination every 1-3 years, starting when colorectal polyposis is diagnosed or at age 20-25
› Annual physical exam including cervical ultrasonography, starting at age 25-30
Prophylactic Surgical Options
- Prophylactic colectomy when polyps become unmanageable
For MUTYH-Associated Polyposis
Surveillance
- Colon & rectum: Colonoscopy every 2 years, starting at age 18-20
- Others:
› EGD including side-viewing examination every 1-3 year(s), starting at age 20-25
Prophylactic Surgical Options
- Prophylactic colectomy when polyps become unmanageable
For Peutz-Jeghers syndrome
Surveillance
- Colon & rectum: Colonoscopy every 2-3 years, starting with symptoms or in late teens
- Others:
› EGD including side-viewing examination every 2-3 years, starting at age 10
› Magnetic resonance cholangiopancreatography and/or endoscopic ultrasound of the pancreas every 1–2 years starting at age 30
› Annual mammogram and breast MRI starting at age 25
› Clinical breast exam starting at age 25
› Annual pelvic examination, Pap smear and transvaginal ultrasound starting at age 18 years
› Annual testicular exam starting at age 10
For Juvenile Polyposis syndrome
Surveillance
- Colon & rectum: Colonoscopy every 2-3 years, starting with symptoms or in late teens
- Others:
› Esophagogastroduodenoscopy every 1-3 years