Frequently Asked Questions

Mayo Clinic Colon Cancer Family Registry Pamphlet (260KB PDF)

What is the Colon CFR?

The Colon CFR is an international consortium of six Registry centers and an Informatics Center. The participating centers are:

  • University of Hawaii - Honolulu, Hawaii
  • Fred Hutchinson Cancer Research Center - Seattle, Washington
  • Mayo Clinic - Rochester, Minnesota
  • University of Southern California - Los Angeles, California
  • University of Queensland - Brisbane, Australia
  • Cancer Care Ontario - Ontario, Canada
  • Research Triangle Institute – Research Triangle Park, North Carolina

This consortium is dedicated to establishing a registry that will assist in discoveries about the causes of colorectal cancers. Currently about 12,000 families from around the world are enrolled. Researchers can apply to the Colon CFR for use of this resource as an efficient way to conduct their research. That is, many different researchers can study the same families instead of each researcher having to recruit their own study population.

How is my privacy and confidentiality protected?

No person’s identity is ever shared with any researcher outside the Mayo Colon CFR and information learned about you through this study does not become part of your medical record. All identities are protected by use of a unique identifier number and only the Mayo CFR study personnel know your identity.

Who can enroll?

If you had colorectal cancer and have two first degree relatives (parents, brother, sister, children) with colorectal cancer, one of which was diagnosed under 50 years of age, you could enroll.


If you had colorectal cancer and your family has a known genetic condition that can cause colorectal cancer, you could enroll.

What is involved?

This project is focused on collection of detailed information on study participants and their relatives to help create a resource that will be helpful to colon cancer researchers. To enroll in the Colon CFR a person must sign a written informed consent and provide a detailed family history. Specific other family members would also be invited to enroll, if the participant is agreeable to their being invited into the study. The enrollee will also be asked to complete a detailed questionnaire about medical history, diet, exercise, medication use and many other lifestyle issues. A blood specimen will be collected. In addition, the investigators will ask for release of medical records and samples of tumor tissue if there is a history of cancer and if that tissue is stored somewhere. No other procedures are required.

This study will not make your health better, nor is there any assurance that you will get any sort of test results from this study. If you would like to consider doing something to help make progress in understanding colorectal cancer, you may be interested in enrolling in this study.

How can I learn more or become involved?

Your Mayo Health Care provider has shared this brief introduction with you because they thought you might be interested in the Colon CFR. Please understand that your current and future care at the Mayo Clinic will not be affected by whether or not you participate. If you would like to learn more about this study, you can call us or write to us at:

Mayo Clinic
Attn: Sherry Gustafson
Charlton 6-124
200 First Street SW
Rochester, MN 55902
1-866-514-8452 (toll-free)

Who has access to my CFR study information?

Access to your personal information is extremely limited and highly protected. Even if information you gave us is used in studies that involve other medical centers and even if your blood specimen is shared with researchers elsewhere, no one outside of our Mayo study group can know who you are. All information is given a code number and only the Mayo study group has the key to the code. Your privacy and confidentiality are safeguarded carefully. We understand how important this is to everyone. No results are entered into your Mayo medical record (if you have one here) and no insurance company has any access to anything we record or study. Confidentiality is a top priority. We try to handle all your information the way we would want ours handled if we were in this study.

NOTE: On May 21, 2008, President Bush signed into law the Genetic Information Nondiscrimination Act (GINA.) This legislation will be the first to prohibit employers and health insurers from discriminating against individuals on the basis of their genetic information. With the passage of this bill, people will be able to participate in research studies without the fear of genetic discrimination. Under the federal protection provided by GINA, health care practitioners will be able to recommend appropriate genetic testing and screening procedures unencumbered by the fear of discrimination based upon the results. The bill had passed the Senate unanimously and the House by a vote of 414 to 1. The long-awaited measure, which has been debated in Congress for 13 years, will pave the way for people to take full advantage of the promise of personalized medicine without fear of discrimination.

Should I have genetic testing?

This question cannot be answered without knowing much more about you as a person. If your history suggests that the odds of having a genetic condition are very small (as is the case for most people with cancer), then it is probably not sensible to test. For those whose cancer history, family history, or tumor testing raise more concern for a hereditary cause for cancer, testing might be reasonable.

Genetic testing can have both risks and benefits. It is important to discuss the decision with a professional (such as a medical geneticist or genetic counselor) before undergoing genetic testing. Both positive and negative results can provide relief and reduce uncertainty about genetic status when a genetic test is used appropriately. A negative test may reduce the need for frequent checkups or surgeries and may create a sense of well being that one is not at increased risk for a disease compared to the general population. A positive test can increase knowledge and encourage an individual to use appropriate preventive measures to reduce risk.

Does Mayo CFR provide free genetic counseling and genetic testing?

The Colon CFR is a research project and is not meant to provide individualized health care advice to you nor be a substitute for having a consultation with a geneticist or having testing done in a clinical laboratory if necessary. Some amount of genetic analysis is being done as part of specific projects, however, and if results are thought to be of high significance to you or your family, then under very restrictive rules, the Colon CFR staff may provide some genetic counseling via the phone in the context of telling you about your option of learning a research result. If you want to explore genetic testing, you should not rely on this study to give you what you need. We are happy to assist you in locating a geneticist in your area.

Will I find out the final results of the study?

We don’t anticipate “final results” in this study, as it is an ongoing study. As we have discussed, there are over 100 individual projects underway that involve some proportion of all CFR enrollees. Any major finding will be published and we plan to continue newsletters such as this to keep you up-to-date. If something potentially highly useful to you is discovered about you individually, you will be contacted to see if you choose to learn about this or not. For many people, no individually useful results will ever be found.

How did you get my tumor block?

This question comes up quite frequently, particularly from participants who did not have surgery at Mayo Clinic. When a patient is first contacted and agrees to participate, they are sent a lot of information, a blood kit, consent form, epidemiology questionnaire and a medical authorization to obtain medical records and tissue blocks from their cancer surgery. When the patient (you) signs the medical authorization form, he or she also lists the name of the institution that we should contact to obtain those records and blocks. We then send this form, along with a letter requesting the material, to the facility listed on the form. Once the tissue blocks are received, slides are made (see next paragraph). The blocks are then returned to the institution.

What happens to my blood and tissue sample in this study?

After blood is drawn, it is sent immediately to Mayo Biospecimen Accessioning and Processing Laboratory. When the tubes arrive, their labels are checked to see that they agree with the paperwork that was sent with them – ensuring they are from the right person. A few drops of blood are spotted onto a special paper for studies that need only small amounts of blood. The remaining blood is spun in a centrifuge to separate the plasma (the liquid component of blood) from the cells. The plasma and the cells are then moved to smaller tubes and stored in a very cold freezer until it is needed for a research project.

For those who had a cancer removed, we may have requested written permission to release the stored tissue from the hospital where your surgery was performed. Once permission is provided, our staff requests the specimens (often called “tissue blocks” because they are embedded in rectangular pieces of wax) from that hospital.

With the arrival of the blocks at Mayo Colon CFR area, blocks are logged into our database, and then ultra-thin slices of tumor tissue are carefully shaved off the blocks to make slides. The slides are examined by a pathologist and a report on that tumor is generated and also recorded in the database. The slides are stored at Mayo for research use but the original blocks are returned to your hospital.

How useful is colorectal cancer screening?

Colorectal cancer is highly preventable if polyps in the colon or rectum are removed. It is believed that nearly all colorectal cancers began as a polyp. It is estimated that only about 1 in 25 polyps will turn into a cancer, but no one can tell which polyp might become a cancer. Therefore, colonoscopic screening with removal of polyps actually prevents colorectal cancers.

How often should colon cancer screening be done?

In March 2008, the American Cancer Society (ACS), the American College of Radiology and the U.S. Multi-Society Task Force on Colorectal Cancer (a group that comprises representatives from the American College of Gastroenterology, American Gastroenterological Association, and American Society for Gastrointestinal Endoscopy), released consensus guidelines for colorectal cancer screening. While these may not be applicable to many of the Colon CFR families, in general, adults age 50 and older are recommended to have regular screening for colorectal cancer using one of the following methods:

Colorectal Cancer Screening Guidelines for Average Risk Persons

  • Yearly guaiac-based fecal occult blood test or fecal immunochemical test — tests that check for blood in the stool and have a high sensitivity for cancer
  • Flexible sigmoidoscopy every five years
  • Colonoscopy every 10 years
  • Double contrast barium enema every five years
  • Stool DNA test – shown effective, although at this time the recommended interval is unknown
  • CT colonography every five years

But if you are in this study, you might not be considered “average risk.” The American Cancer Society provides separate guidelines for screening those at increased and high risk. These are shown in the following tables.

INCREASED RISK — Patients With a History of Polyps on Prior Colonoscopy
Risk Category Age to Begin Recommended
People with small rectal hyperplastic polyps Same as those with average risk Colonoscopy, or other screening options at regular intervals as for those at average risk Those with hyperplastic polyposis syndrome are at increased risk for adenomatous polyps and cancer and should have more intensive follow-up.
People with 1 or 2 small (less than 1 cm) tubular adenomas with low-grade dysplasia 5 to 10 years after the polyps are removed Colonoscopy Time between tests should be based on other factors such as prior colonoscopy findings, family history, and patient and doctor preferences.
People with 3 to 10 adenomas, or a large (1 cm +) adenoma, or any adenomas with high-grade dysplasia or villous features 3 years after the polyps are removed Colonoscopy Adenomas must have been completely removed. If colonoscopy is normal or shows only 1 or 2 small tubular adenomas with low-grade dysplasia, future colonoscopies can be done every 5 years.
People with more than 10 adenomas on a single exam Within 3 years after the polyps are removed Colonoscopy Doctor should consider possibility of genetic syndrome (such as FAP or HNPCC).
People with sessile adenomas that are removed in pieces 2 to 6 months after adenoma removal Colonoscopy If entire adenoma has been removed, further testing should be based on doctor’s judgment
INCREASED RISK — Patients With Colorectal Cancer
Risk Category Age to Begin Recommended Test(s) Comment
People diagnosed with colon or rectal cancer At time of colorectal surgery, or can be 3 to 6 months later if person doesn't have cancer spread that can't be removed Colonoscopy to view entire colon and remove all polyps If the tumor presses on the colon/rectum and prevents colonoscopy, CT colonoscopy (with IV contrast) or DCBE may be done to look at the rest of the colon.
People who have had colon or rectal cancer removed by surgery Within 1 year after cancer resection (or 1 year after colonoscopy to make sure the rest of the colon/rectum was clear) Colonoscopy If normal, repeat exam in 3 years. If normal then, repeat exam every 5 years. Time between tests may be shorter if polyps are found or there is reason to suspect HNPCC. After low anterior resection for rectal cancer, exams of the rectum may be done every 3 to 6 months for the first 2 to 3 years to look for signs of recurrence.
INCREASED RISK — Patients With a Family History
Risk Category Age to Begin Recommended Test(s) Comment
Colorectal cancer or adenomatous polyps in any first-degree relative before age 60, or in 2 or more first-degree relatives at any age (if not a hereditary syndrome). Age 40, or 10 years before the youngest case in the immediate family, whichever is earlier Colonoscopy Every 5 years.
Colorectal cancer or adenomatous polyps in any first-degree relative aged 60 or higher, or in at least 2 second-degree relatives at any age Age 40 Same options as for those at average risk. Same intervals as for those at average risk.
Risk Category Age to Begin Recommended Test(s) Comment
Familial adenomatous polyposis (FAP) diagnosed by genetic testing, or suspected FAP without genetic testing Age 10 to 12 Yearly flexible sigmoidoscopy to look for signs of FAP; counseling to consider genetic testing if it hasn't been done If genetic test is positive, removal of colon (colectomy) should be considered.
Hereditary non-polyposis colon cancer (HNPCC), or at increased risk of HNPCC based on family history without genetic testing Age 20 to 25 years, or 10 years before the youngest case in the immediate family Colonoscopy every 1 to 2 years; counseling to consider genetic testing if it hasn't been done Genetic testing should be offered to first-degree relatives of people found to have HNPCC mutations by genetic tests. It should also be offered if 1 of the first 3 of the modified Bethesda criteria is met.1
Inflammatory bowel disease
-Chronic ulcerative colitis
-Crohn's disease
Cancer risk begins to be significant 8 years after the onset of pancolitis (involvement of entire large intestine), or 12-15 years after the onset of left-sided colitis Colonoscopy every 1 to 2 years with biopsies for dysplasia These people are best referred to a center with experience in the surveillance and management of inflammatory bowel disease.

1 The Bethesda criteria can be found in the "Can Colorectal Cancer Be Prevented?" section of our larger Colorectal Cancer document.

Table reprinted by the permission of the American Cancer Society, Inc. from All rights reserved.

What is genetic testing?

Because genetic testing results are being offered to some Colon CFR participants, we are including general information about this subject.

  • A genetic test can be used to confirm a disease diagnosis or to look for a future predisposition to a disease.
  • A genetic test is usually done by a simple blood test but can also be done by testing other body fluids or tissues.
  • Genes are made up of DNA, the information in our cells that instructs the body how to grow and function.
  • DNA is coded by four chemicals, which are symbolized by the letters A, C, G and T (adenine, cytosine, guanine, and thymine).
  • A genetic test looks for changes, or mutations, in the DNA, which could lead to a disease. Such changes can be as small as a single altered chemical (such as "A" changed to a "C"). Other changes could be much larger, such as a loss of several hundred or thousand chemicals.

Note: The cause of colorectal cancer is still unknown for most people. Less than 5 percent of colorectal cancer is thought to be hereditary. The majority of people who get cancer do not inherit altered genes as the cause of their colorectal cancer, and most Colon CFR participants do not have a recognizable genetic disorder.

How is the Mayo Colon CFR kept up-to-date?

How has your family history changed? When you originally enrolled in the Colon CFR, we collected a family history of cancers from all enrollees. Family histories change over the years with births, deaths, and new diagnoses. We therefore are updating all the family histories by a combination of phone calling and written questionnaires. This helps us have up-to-date information on what is happening in your family. It also provides an opportunity to invite more relatives into this study.

Inviting more family members to enroll. The Colon CFR is a family registry. We are interested in extending an invitation to enrollment to all first-degree relatives (parents, brothers, sisters, adult children) of people who have had colorectal cancer. Having lifestyle questionnaires and blood specimens from your relatives is enormously powerful to researchers who are trying to tease apart the differences between who gets cancer and who does not. It takes studying literally thousands of people to detect small differences that may protect or predispose them to colorectal cancer.