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Knowing Your Risk for Colon Cancer

Scott Weissman March 24, 2009 1:00 PM This chat has ended. Thank you for participating.
Scott Weissman (NorthShore) - 12:49 PM:
On behalf of the Center for Medical Genetics at NorthShore University HealthSystem, I would like to welcome all of you to our online chat discussing the genetics of colon cancer, the importance of family history in determining an individual’s chance of developing colon cancer and how knowing this information could impact colon cancer screening recommendations. By nature, people are always very interested in specific risks to themselves. I will try to answer any questions that I can, but please understand, it is difficult to provide accurate risk assessments in this online chat format. If you have additional questions or more personal questions that you do not want to share in this format, please feel free to email me directly at sweissman@northshore.org sometime after this chat is complete. Thank you and let’s get started…

Beth (Arlington Heights) - 1:01 PM:
Why does your risk for colon cancer increase after the age of 50?

Scott Weissman (NorthShore):
Beth- Thanks for your question. Unfortunately, I do not know that I have the answer to your question. Our risk for any cancer increases as we age. 50 seems to be the age cutoff for cancers considered to be early-onset (if it is diagnoses under the age of 50) and after 50 is considered a "normal" age of onset. I do not know if there is something specific to colon cancer that after age 50 that causes our risk to go up.

Jeremy (Evanston) - 1:06 PM:
What are the most common risk factors for colon cancer?

Scott Weissman (NorthShore):
Jeremy- Common risk factors for colon cancer can be diets that are high in fat, low in fiber or green leafy vegetables and high red meat intake. Another risk factor is family history. Anyone who has a first degree relative (parent, sibling, child) who has had colon cancer has about a 2-fold increase in risk. This would translate to a 10% lifetime risk as opposed to 5% which is the risk everyone faces.

Jeremy (Evanston) - 1:09 PM:
I have heard that eating certain foods can decrease your risk for colon cancer, is there any truth to this?

Scott Weissman (NorthShore):
This is true, please see previous response.

Beth (Arlington Heights) - 1:11 PM:
As an African American am I more vulnerable to colon cancer? Or is ethnicity not a factor?

Scott Weissman (NorthShore):
Ethnicity can be a factor and African Americans can face a slightly higher risk of colon cancer compared to Caucasians and it may have something to do with dietary and environmental factors. People of Ashkenazi Jewish ancestry also face a higher baseline risk of colon cancer than people in the general population.

Walter (Waukegan, IL) - 1:13 PM:
My father has had polyps found and removed from his colon, but never cancerous. Would this make me a candidate for earlier than normal colon screening?

Scott Weissman (NorthShore):
It may. If a first degree relative (parent, sibling, child) has had a precancerous colon polyp (called an adenoma) under the age of 60, it is recommended by the American Gastroenterological Association that the children and siblings of this individual have a baseline colonoscopy at age 40 instead of age 50 and have them repeated every 5 years instead of every 10.

Rebecca (Evanston, IL) - 1:15 PM:
I know that carriers of the BRCA1 or BRCA2 mutation are more susceptible to developing breast or ovarian cancer, but is there any correlation to colon cancer?

Scott Weissman (NorthShore):
Really good question. Some studies have found an increased risk of colon cancer with BRCA mutations; other studies have not found this, so the association is controversial. Generally, we tell people who have a BRCA mutation to start colonoscopies at age 40 and have them repeated every 5 years. This is not a standard recommendation, but we have a number of BRCA positive families with colon cancer, so we tend to err on the side of caution.

Jeremy (Evanston) - 1:17 PM:
What exactly are polyps and how are they formed?

Scott Weissman (NorthShore):
The simple explanation is that a polyp is a growth of cells from the layer of colon tissue that is closest to the surface. The cells generally acquire DNA damage from daily living and over time this can cause the cells to grow out of control and form a polyp. There are various types of polyps and 50% of adults will have at least 1 over the course of their life. Some polyps have NO malignant potential and others, like adenomas, do have the chance to turn into cancer if they are not removed.

Susan (Winnetka) - 1:21 PM:
If you already are a carrier of a gene that can potentially cause colon cancer, are there lifestyle changes or modifications that can be implemented to reduce or mitigate the risks of getting the disease?

Scott Weissman (NorthShore):
Susan, while we would like to believe that diet (e.g., low in fat, high in fiber) and exercise would play a role in mitigating the risk of developing colon cancer if you carry a hereditary predisposition, there is no data out there that I could quote you that says diet and exercise reduce or modify the risk. There is some data that aspirin and certain non-steroidal antiinflammatory medications like sulindac can reduce the risk of polyp formation, so in turn this may help decrease the risk. If you have additional questions specific to your situation, please do not hesitate to contact our office for additional help (847-570-1029).

Walter (Waukegan, IL) - 1:27 PM:
How fast does colon cancer develop and advance?

Scott Weissman (NorthShore):
For a long time, the belief has been that it takes 8-10 years for an adenoma (precancerous polyp) to develop into a cancer. Once a cancer forms, it may take 2-3 years for that cancer to advance and metastasize. There is some very recent data that suggests it may take 17 years for a polyp to turn into a cancer, but this data needs to be confirmed in additional studies.

James (Wilmette) - 1:30 PM:
I know that family history plays a significant role in helping to determine what cancers are prevalent within a family and first relatives with polyps raise a concern/risk, but where do we start looking in our family history? How far back in the family tree do we need to go?

Scott Weissman (NorthShore):
The best place to start and look is with your first and second degree relatives (parents, siblings, children, grandparents, aunts/uncles). If you find that there is a history of cancer/polyps, I would encourage you to go as far back as you can; great aunts, uncles, first cousins, great grandparents. The more information you have, the more accurate a risk assessment a healthcare professional could provide to you. The NorthShore website has a family history drawing program called My Generations (www.northshore.org/mygenerations) that allows you to start drawing a family tree; it will also do a preliminary colon cancer risk assessment based on the information you provide. Of note, it does not take into account polyps, so if you find multiple people with polyps, you may want to contact us directly (847-570-1029).

Jeremy (Evanston) - 1:34 PM:
How much do other conditions such as IBD increase your risk for colon cancer?

Scott Weissman (NorthShore):
Jeremy- This is outside of my knowledge base. You should contact a gastroenterologist to answer this question.

Jeremy (Evanston) - 1:36 PM:
Does drinking alcohol affect my risk factor for colon cancer?

Scott Weissman (NorthShore):
It does, but I do not know to what extent.

Beth (Arlington Heights) - 1:40 PM:
How many people under 50 develop colon cancer?

Scott Weissman (NorthShore):
I am not sure what percentage of people who get colon cancer are diagnosed under the age of 50 of the top of my head. The American Cancer Society or National Cancer Institute keep statistics like this and they may have them on their website.

Beth (Arlington Heights) - 1:41 PM:
I read somewhere that working night shifts for a long time can affect your risk, is this true?

Scott Weissman (NorthShore):
I really do not know if changes to your circadian clock (i.e., working night shifts) would have a negative effect on your risk.

Frank (Chicago) - 1:42 PM:
What are the most common types of colon cancer linked to genetics?

Scott Weissman (NorthShore):
Most colon cancers that are due to a hereditary predisposition are the standard adenocarcinomas. People with Lynch syndrome (also referred to as HNPCC) tend to develop cancers in the right (or ascending) colon and they can have specific pathological features like signet rings (a special cell type in the cancer)or produce mucin (a clear jelly like substance) that may trigger a referral to a genetics professional if these features are seen. Individuals who have familial adenomatous polyposis (FAP) may get diagnosed with colon cancer in the setting of hundreds of polyps in the colon. These 2 hereditary syndromes are the most common colon cancer syndromes.

Walter (Waukegan, IL) - 1:46 PM:
Since colon cancer develops relatively slowly, if you are regularly screened, is there still the possibile risk of death?

Scott Weissman (NorthShore):
The risk of death if you are screening regularly is low but it is not zero. It really depends on how large the cancer is, how aggressive the cancer cells look under the microscope and whether the cancer is found in the lymph nodes at the time of diagnosis.

Frank (Chicago) - 1:49 PM:
Are there specific tests for hereditary colon cancer?

Scott Weissman (NorthShore):
Yes there are. There are blood tests available to determine if someone has inherited a mutation in a gene known to cause hereditary colon cancer. There are currently about 10 or so genes available at specialized labs to determine if someone has a hereditary colon cancer syndrome. We generally use the personal and family history as a guide to determine which gene should be tested. In some situations, we actually need to test the actual colon tumor itself before we can do a blood test. The other key point is that when genetic testing is done, you really need to start with someone in the family who has had colon cancer. Part of the reason for this is that none of our genetic tests are 100% accurate which means in certain siutations, a negative gene test can be falsely negative.

Kristin Philbin (Moderator) - 1:50 PM:
Thank you everyone for your great participation, the chat will be ending in approximately 10 minutes. Please submit any final questions you have.

Jeremy (Evanston) - 1:55 PM:
How invasive are the screenings for colon cancer?

Scott Weissman (NorthShore):
The most invasive test is the colonoscopy. I think the risk of a perforation (tearing the colon tissue) is about 1 in every 1000 procedures. Otherwise, things like fecal occult blood tests, fecal DNA tests, barium x-rays are not very invasive at all.

Kristin Philbin (Moderator) - 1:58 PM:
Thank you again for participating in our chat today. For more information please visit our Colon Cancer pages.


Scott Weissman (NorthShore) - 1:59 PM:
Thank you all for your participation in today's chat. Again, if you have additional questions or concerns, please feel free to contact the Center for Medical Genetics at 847-570-1029 or visit us online at www.northshore.org/medicalgenetics.
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