This information is designed for individuals who have been tested for a hereditary cancer syndrome. It will help you understand the results of your test and is best reviewed with your healthcare provider. Please choose the link below that matches your test result by looking at the patient copy of your test result or contacting the healthcare provider who ordered your test.
Overview of FAP and AFAP
Mutations in APC cause one of two adenomatous polyposis syndromes: familial adenomatous polyposis (FAP) or attenuated familial adenomatous polyposis (AFAP). These syndromes are associated with the development of varying numbers of adenomas (pre-cancerous polyps) in the colon and rectum.
| Number of Colorectal Adenomas (Polyps) |
|
| Familial Adenomatous Polyposis (FAP) | Hundreds to thousands |
| Attenuated FAP (AFAP) | Between 10 and 99 over a lifetime |
The Genetic Test(s) You Received
- Comprehensive COLARIS AP®:
Full sequence and large rearrangement
analysis of the APC gene and a
mutation panel of the MYH gene.
- Gene-Specific COLARIS AP® APC Analysis: Analysis of only one of the genes
responsible for HNPCC syndrome: MLH1, MSH2, or MSH6.
- Singe Site COLARIS AP®: Mutation-specific analysis for
individuals with a known APC gene
mutation in the family.
Your Test Result
- Positive for a Deleterious Mutation
- Genetic Variant, Suspected Deleterious
Overview of Your Test Result
- You have a mutation or alteration in the APC gene.
- You have an adenomatous polyposis syndrome (either FAP or AFAP, depending on the number of colorectal adenomas).
- FAP and AFAP increase the risk of colorectal adenomas/cancer, and in some cases, other types of cancer.
- The risk of developing these cancers is less than 100%. Not everyone with FAP or AFAP will develop cancer.
Your Cancer Risks
Having FAP or AFAP increases the risk of certain cancers.
| Colorectal cancer risks by age 70 | Mutation Carrier |
General Population |
| FAP | ~100% | 2% |
| AFAP | 80-100% |
| Other cancer risks by age 70* | Mutation Carrier |
General Population |
| Duodenal cancer | 4-12% | <1% |
| Thyroid cancer | ~2% | <1% |
| Pancreatic cancer | ~2% | <1% |
| Hepatoblastoma (liver cancer in children) | 1.6% | <1% |
| Brain cancer | <1% | <0.6% |
| Stomach cancer | 0.6% | <1% |
* Less information is available about the risks of these cancers than about colorectal cancer.
Managing Your Risks
Options for reducing cancer risk are available whether or not you have already had a cancer diagnosis. The following are medical management guidelines for individuals with HNPCC syndrome. Discuss these options with the appropriate medical professionals to determine how you will manage your cancer risks.
Increased Surveillance
| Site | Procedure | Age to Begin | Repeat |
| Colon | Colonoscopy | 20-25 years (or 5-10 years earlier than the youngest colorectal cancer in the family, whichever comes first) |
1-2 years Annually after age 40 |
| Endometrium (Uterus)/Ovaries |
Gynecologic exam Transvaginal ultrasound Endometrial aspiration (tissue sample) CA-125 |
25-35 years | 1-2 years |
Screening for other related cancers (brain, pancreatic, hepatoblastoma, etc.) may be considered. Please speak to your healthcare provider about this option.
Surgical Management
- FAP – Preventive removal of the colon and rectum is recommended. The timing of surgery is based on the number/size of polyps.
- AFAP – Preventive removal of the colon and rectum may be recommended depending on the number of polyps.
Chemoprevention
- Drugs may be used to reduce the number of polyps in any rectum that remains after colon surgery.
It’s a Family Affair
APC mutations are passed on in a family. Now that a mutation has been identified in you:
- Your close blood relatives (parents, children, brothers, and sisters) have a 50% chance of having the same mutation.
- More distant relatives (cousins, uncles, and aunts) also have a chance of having the mutation that runs in your family.
- Generally, the mutation is only going to be found on the side of your family (father's or mother's) that has the history of cancer and/or adenomas.
Note: If you have no family history of adenomas and/or cancer, it is possible the APC mutation is new in you. Your parents can be tested for your mutation to confirm that this is the case. In this situation, your children have a 50% chance of having the same APC mutation and there is a small chance that your brothers and sisters might also have the mutation. However, your more distant relatives are not at-risk.
Your relatives can be offered Single Site COLARIS AP® to determine whether or not they have the same mutation.
- Relatives interested in genetic testing will need to know your specific mutation. It is best to provide your relatives with a copy of your test result which you can obtain from your healthcare provider.
- If your relative is:
- Positive for the mutation, he/she has the increased cancer risks associated with FAP or AFAP and can benefit from appropriate medical management.
- Negative for the mutation, he/she has an average risk of cancer and can follow general population screening guidelines.
Your healthcare provider can assist in determining which of your relatives should consider genetic testing.
If you need a copy of your genetic test result, please contact the healthcare provider who ordered your test.
Next Steps
Please work with your healthcare provider to determine the most appropriate next steps for you.
- Obtain a copy of your test result.
- Schedule consultations with appropriate healthcare providers.
- Create a plan for medical management.
- Share your genetic test result with your relatives (identify your specific mutation so relatives can have Single Site testing).
- Re-contact your healthcare provider on a regular basis for new information about FAP and AFAP.
Additional Resources
Myriad has resources available to help you with your genetic test result.
- Contact Myriad’s Medical Services Department at 1-800-469-7423 for:
- Answers to questions about your test result.
- Information about genetic testing for your relatives.
- Online tools:
- List of Support Organizations
- A healthcare provider who can offer genetic testing to relatives in any state can be found at the Find a Doctor page.
- A sample letter that can be sent to relatives who may need genetic testing: letterCOAP1Positive (Word)
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