Colon Cancer: Genetic Experts Eager to Answer Your Questions
Online Health Chat with Dr. Charis Eng and Dr. Matthew Kalady
March 18, 2011
Cleveland_Clinic_Host: Did you know colon cancer is one of the most common cancers? If detected early, it's also one of the most curable. Cleveland Clinic colorectal surgeon Matthew Kalady, MD, and genomic researcher and clinician Charis Eng, MD, PhD will provide answers to your questions about your family history and the genetic components of colon cancer. Keep in mind that the presence of abnormal genes that are related to a certain disease does not mean that a person or his or her children will develop the disease. It means that a person has a higher than average risk for the disease. However, external factors, such as environment exposures and diet, might play a role in whether a disease develops.
Charis Eng, MD, PhD, Hardis Chairwoman of the Genomic Medicine Institute and American Cancer Society Professor at Cleveland Clinic, is the founding Director and attending clinical cancer geneticist of the Institute’s clinical component, the Center for Personalized Genetic Healthcare. She is also Professor and Vice Chairman of the Department of Genetics at Case Western Reserve University School of Medicine.
Matthew Kalady, MD, is an Assistant Professor of Surgery in the Department of Colorectal Surgery in Cleveland Clinic’s Digestive Disease Institute. He has a clinical and scientific interest in the causes and treatment of colorectal cancer, including hereditary colorectal cancer syndromes. He is Vice-Chair of the Sanford D. Weiss, MD, Center for Hereditary Colorectal Neoplasia, and Head of the Hereditary Nonpolyposis Colorectal Cancer Section of the Jagelmen Registries. Dr. Kalady also holds the Krause-Lieberman Chair in Colorectal Surgery.
To make an appointment with Charis Eng, MD, PhD, or any of the specialists in the Genomic Medicine Institute at Cleveland Clinic, please call 216.636.1768 or 800.998.4785 (toll-free). You can also visit us online at http://my.clevelandclinic.org/genomics-genetics/genetic-genomic-medicine.aspx.
To make an appointment with Matthew Kalady, MD, or any of the specialists in the Digestive Disease Institute at Cleveland Clinic, please call 216.444.7000 or call toll-free at 866.382.0089. You can also visit us online at www.clevelandclinic.org/score.
Cleveland_Clinic_Host: Welcome to our Online Health Chat with Drs. Matthew Kalady and Charis Eng. We are thrilled to have them here today for this chat. Let’s begin with the questions.
Colon Cancer Defined
cupcake: What causes colon cancer?
Dr__Matthew_Kalady: Colon cancer arises from a series of accumulated defects, or changes, in the normal lining of the colon. These defects can be caused by a number of factors. Some are genetic and hereditary, which we cannot control. Others are related to environmental and dietary exposures, as well as lifestyle influences.
A common association is a diet that is high in fat and red meat, and low in fiber. We generally recommend a low-fat, high-fiber diet for colon health. As a general rule, plenty of fruits and vegetables are also recommended.
Obesity and diabetes have been linked with a greater risk of colon cancer, and a lack of physical exercise has also been associated with an increased risk.
crans: What are “hereditary colon cancer syndromes”?
Dr__Charis_Eng: Hereditary colon cancer syndromes represent 5 percent to 15 percent of all colon cancers that are due to inherited, altered genes. For example, Lynch syndrome is the most common hereditary colon cancer syndrome. In the West, the syndrome predisposes individuals to colon, uterine, and ovarian cancers.
Peutz-Jeghers syndrome is another type of hereditary colon cancer syndrome that is caused by a different altered gene. This syndrome is associated with colon, pancreas, and breast cancers.
Dr__Matthew_Kalady: At Cleveland Clinic, we specialize in hereditary colorectal cancer syndromes. We have a multi-disciplinary team of doctors and nurses who oversee all aspects of patient care. The Jagelman registry within the Weiss Center is the largest registry of this kind in North America.
cocob: How common is colorectal cancer?
Dr__Charis_Eng: There are approximately 145,000 new cases of colorectal cancer in the United States and 1 million cases throughout the world every year. In the United States, it is the third most common form of cancer, and the second most common cause of cancer-related death. Approximately 1 in 20 people in the United States will develop colorectal cancer in his or her lifetime.
jacob: How often is colorectal cancer hereditary?
Dr__Charis_Eng: About 5-10 percent of all colorectal cancer is caused by a known hereditary genetic defect. In addition, about another 20 percent of colorectal cancer is believed to be linked within families, and members of that family are at an increased risk of developing colorectal cancer. However, we do not know the exact gene or defect that is the underlying cause.
pandas: What kind of doctor should I see? My primary care doctor?
Dr__Matthew_Kalady: Colorectal cancer is best treated by a colorectal surgeon who has specialty training for this disease. Depending on the stage of the cancer, a medical oncologist may be part of the team to deliver chemotherapy. Your primary care doctor is the best place to start to discuss any symptoms or the need for screening. If your doctor finds something unusual, then referral to a colorectal surgeon is appropriate. If there is a family health history suggestive of colon or other cancer clusterings, then the primary care doctor should refer to genetics professionals.
pjt: Who should consider genetic counseling and testing?
Dr__Charis_Eng: This is an excellent question because it alludes to genetic counseling before gene testing. First, look at your family history. There are certain “red flags” that suggest a cancer might be due to genetics. If a red flag shows up, you might want to see a genetic counselor. The red flags include:
- Young age of onset
- Bilateral (both sides) involvement in paired organs (eg, both breasts have cancer)
- Clustering of certain cancers that form a pattern (For example, colon and uterine cancer suggests Lynch syndrome.)
- Clustering of cancers in families
cc: Can you do a blood test or something to detect colon cancer? Isn't there a cancer gene that can be tested for?
Dr__Charis_Eng: Detecting colon cancer (the cancer itself) and looking for the presence of a colon cancer gene that predisposes a person to colon cancer are different. Inheriting a colon cancer gene predisposes a person to colon and other cancers (depending on the specific gene), but it does not mean that individual will definitely get cancer. Currently, there is no blood test to detect for colon cancer per se.
BRESSA: What are some ways to reduce the risk of colon cancer?
Dr__Matthew_Kalady: The best way to reduce the risk of colon cancer is to adhere to a recommended screening regimen. We know that colon cancers are developed from the normal lining of the colon to a precancerous polyp and then to a cancer. Therefore, detecting polyps before they become cancer and having them removed is the best way to reduce the risk.
There are also several behavioral and dietary modifications that can reduce formation of polyps and cancer. These include exercising regularly, not smoking, and eating a diet rich in fruits and vegetables, and low in fat.
cc: My mother had colon cancer when she was 37. Eleven inches were removed and she had radiation. It's been 28 years and she is still cancer-free. There is no other colon cancer in our family; in fact, no cancer. Could this be a genetic thing that can be passed down to me? I am 42 and have regular colonoscopies since I was 30, and all is fine.
Dr__Charis_Eng: First, it is great news that your mom is cancer-free for this long. The average age at diagnosis of colon cancer is 55 to 60 years old, so 37 is quite young. Young age at diagnosis is one red flag that suggests genetics. I would suggest you seek a genetics evaluation. The genetics professionals at Cleveland Clinic are happy to serve you. See: http://my.clevelandclinic.org/genomics-genetics/genetic-genomic-medicine.aspx or call 216.998.4785.
lahmeh: My mother died of colon cancer at 50. I've had a colonoscopy at 37. My doctor says I don't need to worry about another screening until I'm 42 and probably every five years or so after. Do you think that is enough screening or should I get a second opinion.
Dr__Matthew_Kalady: It depends on what your colonoscopy looked like at age 37. If it was completely normal, then five years is a rational plan. It also would depend if there was any other history of colon cancer in your family.
Brian_K: What if my mother/father/grandparents had colon cancer?
Dr__Charis_Eng: This situation sounds like a familial clustering of colon cancers (one of the red flags that suggests something genetic), and you should seek an evaluation by genetic professionals. The genetics professionals at Cleveland Clinic are happy to serve you. See: http://my.clevelandclinic.org/genomics-genetics/genetic-genomic-medicine.aspx or call 216.998.4785.
You can also look for a genetic counselor anywhere in the country at the National Society of Genetic Counselors Web site http://www.nsgc.org/tabid/69/Default.aspx.
Keep in mind that if you think you have a hereditary colon cancer or if you have a family history with cancer, you should seek out professionals trained in cancer genetics. For example, you should ensure that the genetic counselor is a cancer genetic counselor and that the physician who is overseeing the genetic counselor is a doctor who is formally trained in cancer genetics (not just medical genetics or not just oncology).
jh: What is a “family health history”? Should I get that done?
Dr__Matthew_Kalady: It is important to know what diseases exist or may run in your family. Colon cancer is one of those diseases. There is an increased risk for all first-degree relatives of people with colon cancer. A first-degree relative is an immediate family member, such as your parents, siblings, or children. Even those with extended family member who have had cancer (grandparents, aunts, uncles) have a higher risk than the general population. Therefore, it is important to know your family history so appropriate risk can be determined and your screening can be individualized.
jugler: For someone with a strong family history of colon cancer, when do you recommend beginning to get colonoscopies? When would you suggest genetic counseling?
Dr__Charis_Eng: Someone with a strong family history of colon cancer should first be evaluated by a professional in genetics, because there are different colon cancer genes. Genetic testing for colon cancer will give an accurate diagnosis of the type of hereditary colon cancer gene a person has. Depending on which gene is involved, it will tell your health care providers how to personalize your treatment. Usually, it will tell the doctor to begin routine colonoscopies at a younger age -- for example, age 25 instead of 50 (because the colon cancers can occur before the age of 30) -- and with greater frequency -- annually instead of every 10 years. Also, depending on the specific gene, it will also tell your health care provider which other organ needs to be watched. Genetic knowledge is power.
Knowing which gene is altered will also allow the genetics professionals to offer gene testing (only looking at that one spot in that specific gene) to your unaffected family members. This is a 100 percent accurate test that will let them know whether they carry the same gene risk or not. If they do, then they can receive the same close clinical screening to catch cancers early (when they are curable) or to even prevent cancer from occurring.
The genetics professionals at Cleveland Clinic are happy to serve you. See:http://my.clevelandclinic.org/genomics-genetics/genetic-genomic-medicine.aspx or call 216.998.4785.
cameron: I am scheduled soon for my first colonoscopy. I have a grandfather who died from colorectal cancer, as well as a couple of other family members who have been diagnosed. I have two children. If I come back ‘clean,’ would you recommend having the genetic test? How about for my children (and when)? They are now 12 and 14.
Dr__Matthew_Kalady: A detailed family history and the ages at which colon cancer developed is very important. There are other cancers -- such as uterine, ovarian, and stomach -- that are also associated with certain colorectal cancer syndromes. These are important to mention when you are providing information for your family history. Based on that, your physician can decide who in the family, if anyone, should be tested. It is best to test someone who has a known cancer. If that person has a positive test result, then it might be appropriate for certain other family members to undergo the same test.
In your particular situation, unless more information is known, genetic testing for you and your children is not recommended at this time.
shells: I have read that risk increases with blood relatives having colon cancer. What if I have several relatives with cancer, but no 'immediate' family member with it? How does this increase my risk?
Dr__Charis_Eng: It is difficult to tell with what you have told us here. Because gene testing should always start with the affected (with the colon cancer) relatives, having one of your relatives who had colon cancer go for a genetics evaluation would be ideal. The relative who would provide the most information would be the one with the youngest age at diagnosis.
decide: How do I know if I have colon cancer?
Dr__Charis_Eng: The only way to definitively know if you have colon cancer is to be evaluated for it. There are many different ways of screening for colon cancer. Colonoscopy is considered the standard because it not only can detect cancer and precancerous polyps, it can also serve as a way to biopsy the abnormal tissue for diagnosis; and in some cases, the doctor can completely remove the polyps before they become cancer. You should have a discussion with your physician to see if and when you should undergo a colonoscopy.
Oftentimes, colon cancer or precancerous polyps do not produce any symptoms. In other words, there is nothing that suggests they are there. That is one of the reasons colonoscopy is so important as a screening tool. Sometimes, patients will have symptoms that could be caused by colon cancer, such as a change in bowel habits (for example, new onset of constipation or need to strain, diarrhea, and/or thinning of the caliber of stools), crampy abdominal pain, or bleeding from the anus with or without bowel movements. These symptoms should be evaluated by a physician who can determine if you need a colonoscopy.
BRESSA: My mom had colon cancer four years ago. I'm 33 years old. At what age should I start getting checked for colon cancer? My mom was 55 years old at that time.
Dr__Charis_Eng: The average age at diagnosis of colon cancer is 55 to 60 years old, so your mom is in that average. If she and her family members do not have other cancers, then your colonoscopic screening can begin at 50 years (as with the general population) or sometime in your late 40s.
Dr__Matthew_Kalady: The recommendation is to start screening at an age 5 to 10 years younger than the youngest cancer in your family. Therefore, it is reasonable to be screened at age 45.
movin: What other forms of screening are available for colon cancer?
Dr__Charis_Eng: There are multiple options available for screening for colorectal cancer, including colonoscopy, barium enema with air contrast radiography, flexible sigmoidoscopy, fecal occult blood testing, and fecal DNA testing. Each has advantages and limitations related to accuracy, prevention, costs, and risks and options. You should discuss these with your doctor. A positive result from any of the tests warrants evaluation by colonoscopy. One guideline recommends the following tests and intervals as options for screening:
Tests that detect adenomatous polyps and cancer
- Flexible sigmoidoscopy every 5 years, or
- Colonoscopy every 10 years, or
- Double-contrast barium enema every 5 years, or
- Computed tomographic colonography every 5 years
Tests that primarily detect cancer
- Annual guaiac-based fecal occult blood test with high test sensitivity for cancer, or
- Annual fecal immunochemical test with high test sensitivity for cancer, or
- Stool DNA test with high sensitivity for cancer, interval uncertain
Reference: “Screening and Surveillance for the Early Detection of Colorectal Cancer and: Adenomatous Polyps, 2008: A Joint Guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology” CA Cancer J Clin 2008;58;130-160
snoozer: How do you take a genetic test? Do I need to prepare?
Dr__Matthew_Kalady: A genetic test is a blood test and no preparation is needed.[Umm … how about gathering family history?]
JJ: Who should get a genetic test?
Dr__Charis_Eng: Do not ask your doctor to do a genetic test. Instead, ask to be referred for a cancer genetics evaluation by a genetics professional. This includes genetic counseling.
A genetic evaluation entails assessing you and your family’s health history to look for patterns that suggest there is a genetic risk of colon cancers. Genetic counseling informs and educates patients on what genetics is, as well as the benefits and risks of gene testing.
A professional genetic evaluation will also ensure that the correct gene is tested. There are many genes that predispose to colon cancer; and depending on which particular gene is altered, other types of cancers may be involved as well.
CanfieldOH: If a person experiences colorectal cancer in her early 30s, and genetic testing does not indicate Lynch/HNPCC or other genetic abnormalities, is there any indication for her children to also have genetic testing once they start getting scoped in their early 20s?
Dr__Charis_Eng: There are many genes that associate with colon cancer, so it is important that the individual is evaluated by a professional in genetics. A professional genetics evaluation will also ensure that the correct gene is tested.
Let's suppose that the person has been to a bona fide cancer genetics professional for evaluation, the test is negative, and there is no family history. In that case, the person's relatives should undergo screening 5 to 10 years (most say 10 years) before their early 30s (so early 20's).
If the family history looks like it is truly Lynch syndrome but the gene mutation cannot be found, then the family needs to be treated like it is Lynch syndrome, with annual colonoscopies beginning in the early to mid-20s. For women, endometrial screening is also important because other organs at risk include the ovaries.
MartinT: What happens during a genetic test?
Dr__Charis_Eng: Most genetic tests involve a blood draw. Genetic testing usually takes two to eight weeks to complete. (Ten years ago, this took one year.) Once the results come back, the genetics professional will help interpret the results, and your doctors can use the gene test results to personalize your screening schedule and/or treatment.
January: What are the possible benefits and risks of genetic testing for colon cancer?
Dr__Charis_Eng: If you have colon cancer, genetic testing will give an accurate diagnosis of the type of hereditary colon cancer you have. Depending on which gene is involved, it will tell your health care providers how to personalize your treatment. Also, depending on the specific gene, it will also tell your health care provider what other organs needs to be watched.
Knowing which gene is altered will also allow the genetics professionals to offer gene testing to your family members. This will let them know whether or not they carry the same gene risk. If they do, then they can receive close clinical screening to catch cancers early (when they are curable) or to even prevent cancer from occurring.
Howard: If I have a genetic history of colon cancer in my family, will I still get sick? Can you do anything to prevent it?
Dr__Charis_Eng: If there is a faulty gene running in your family, you should visit a genetics professional who can test you for the presence or absence of the fault (this is 100 percent accurate). Not finding the genetic alteration in you would mean you would revert to population risks. Finding the family-specific gene alteration means your doctors can personalize your management, including increased screening and maybe prevention, depending on which gene is involved.
The genetics professionals at Cleveland Clinic are happy to serve you. See: http://my.clevelandclinic.org/genomics-genetics/genetic-genomic-medicine.aspx or call 216.998.4785.
mojo: After testing, what next?
Dr__Charis_Eng: Always ask for a cancer genetic evaluation by genetics professionals, which includes genetic counseling.
jk: What does genetic counseling consist of? What do the results tell you?
Dr__Charis_Eng: Genetic counseling is the process of helping people understand and adapt to the medical, psychological, and familial implications of genetic contributions to disease. This process integrates:
- Interpretation of family and medical histories to assess the chance of disease occurrence or recurrence
- Education about inheritance, testing, management, prevention, resources, and research
- Counseling to promote informed choices and adaptation to the risk or condition.
229890: If you have genetic counseling for colon cancer, what good does it really do? If you are predisposed for it, knowing in advance won't help you from getting it.
Dr__Charis_Eng: Actually, this is a very widespread myth. Knowing ahead of time is empowering and allows increased clinical screening and prevention.
nyst: Lately a number of my friends in their 40s & 50s have been diagnosed with colon cancer. Why does there seem to be an increase all of the sudden?
Dr__Matthew_Kalady: The incidence of colon cancer for all ages is actually decreasing. This is likely due to the fact that there has been increased use of screening procedures so that precancerous lesions are being detected and removed before becoming cancer. It may seem like there is an increase in younger patients getting cancer because they are your friends, but that is not the trend nationwide. We know that people of all ages can be affected by colorectal cancer; however, it is unusual to develop cancer before age 50.
kreep: I have read an article about Ashkenazi Jews being more predisposed to hereditary colon cancer. If one is an Ashkenazi Jew, does one need genetic testing even if there is no family history?
Dr__Charis_Eng: Epidemiologic data (i.e., population counts) do show that as a group, Ashkenazi Jews do have an increased frequency of colon cancers. One particular gene mutation APC I1307K is an Ashkenazi mutation that increases colon cancer risk two-fold (so instead of a 5 percent lifetime risk, it may be a 10 percent lifetime risk). Currently, we do not recommend testing for this mutation, but instead suggest increased colonoscopic screening.
If you are concerned about a family history, then you should seek cancer genetics evaluation. The genetics professionals at Cleveland Clinic are happy to serve you.
Cleveland_Clinic_Host: I'm sorry to say that our time with Drs. Matthew Kalady and Charis Eng is now over. Thank you both again, for taking the time to answer our questions about Colon Cancer Genetics.
Dr__Charis_Eng: Because genetics research has exploded in the last 10 years, genetics, including a family health history, has become very useful in the clinical setting. Knowing a family cancer history and receiving genetic information from knowledgeable genetics professionals are empowering and can alter medical management and even lifestyles. The genetics professionals at Cleveland Clinic's Center for Personalized Genetic Healthcare are happy to serve you. See: http://my.clevelandclinic.org/genomics-genetics/genetic-genomic-medicine.aspx.
Dr__Matthew_Kalady: Thank you very much for your questions and interest in colorectal cancer.
- To make an appointment with Charis Eng, MD, PhD, or any of the specialists in the Genomic Medicine Institute at Cleveland Clinic, please call 216.636.1768 or 800.998.4785 (toll-free). You can also visit us online at http://my.clevelandclinic.org/genomics-genetics/genetic-genomic-medicine.aspx.
- To make an appointment with Matthew Kalady, MD, or any of the specialists in the Digestive Disease Institute at Cleveland Clinic, please call 216.444.7000 or call toll-free at 866.382.0089. You can also visit us online at www.clevelandclinic.org/score.
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