The Serious Issue of Colon Cancer Screening

Complimentary Story
March 2023

   It’s alimentary, my dear Watson.

   March is colorectal cancer month.  This is a very serious, but sensitive subject.  Having lost a family member to this cancer, I take it personally, offering screening to all my patients.  Given that colon cancer is the fourth leading cause of cancer in the United States, I imagine that most of the readers have also been affected by this diagnosis in one way or another.  In Wisconsin, the rate of colon cancer is 470-500 per 100,000 people, placing us in the top 20% of the nation for the diagnosis of colon cancer.  While likely not entirely preventable, a significant dent can be made in the prevention and early diagnosis of colon cancer by appropriate screening. 

   Current recommendations for colon cancer screening recently dropped from age 50 to age 45.  This change reflects the fact that as more individuals have been screened over age 50 and their precancerous polyps have been removed, fewer people over age 50 go on to develop colon cancer.  As a result, the percentage of new colon cancer diagnoses in persons aged 45-50 seems to have increased as a percentage of new diagnoses, but the total number has also increased.

   Why is that?  Let’s examine some risk factors for the development of colon cancer.  Family history is of course important.  Beyond that, male gender, older age, obesity, sedentary lifestyle, high fat foods, red and especially processed meats, diabetes, smoking, alcohol consumption and low socioeconomic status.  Taking these risk factors into account may explain why Wisconsin is near the top of the list for colon cancer.  

   There are just a few methods to screen for colon cancer.  Stool tests have been around a long time.  The basic ones look for blood in the feces.  They are simple and inexpensive but not too reliable at diagnosing colon cancer.  More than blood can turn the test positive.  Even if it is a true positive, the test does not isolate the region of the intestine where the blood is coming from.  So in the end, maybe this is a good thing as the work up then requires upper and lower endoscopy to see if the problem is in the esophagus or stomach as a colonoscopy does not examine those regions of the intestinal tract.  

   Cologuard is a newer stool test.  This is more specific for colon cancer as it looks for the DNA of colon cancer.  This test does have a higher false positive rate than I would care for, but it is non-invasive and requires no prep, time off work or a driver to get you to and from the test center.  A colonoscopy is required for any positive test.  Personally, I believe this test may be better as a follow up to a normal colonoscopy.  

   Flexible sigmoidoscopy with barium enema was used in the past but reserved for very few today.  As a two test screening, it isn’t very convenient for the patient and may still result in needing a colonoscopy.  

   Colonoscopy is the definitive test for colon cancer screening and early detection.  This test looks for polyp, small growths, that given time deteriorate into cancer.  There are still misses with this test, but that is uncommon. Colonoscopy allows for removal of these polyps so that they do not develop into cancer.  As the invasiveness of the test increases so do the seriousness of the complications such as colon perforation.  Fortunately the risk of a complication is pretty small.  For those concerned about colonoscopy complications, I fall back to the stool tests, but if colonoscopy is off the table, then is it appropriate to even offer any testing?

   I am asked about a couple of other tests that people have heard about.  Colonography, or virtual colonoscopy, has been around for many years already.  It hasn’t caught on for a couple of reasons though.  The prep is the same as doing a colonoscopy and if not done perfectly, may produce artifacts that look like polyps.  A colonoscopy is then required to get a tissue diagnosis.  Some centers schedule this as a dual test so that the colonoscopy can be completed immediately after the questionable colonography, but then back to the driver, time off, etc discussion.

   Another screening test I get asked about fairly often is blood testing.  I have seen several tests that are in development and expect these to become more mainstream in the future.  Any positive test will, as mentioned before, require a follow up colonoscopy to define the problem better and plan treatment.  But if it is negative there is no need for an invasive test.

   So what about prevention?  I have already mentioned the risk factors.  Some are modifiable, some are not.  The modifiable risk factors are best practiced over a lifetime.  Starting late is better than not starting at all since no one knows when the tissue goes from harmless to harmful.  I said this last month, the closer to the garden that you can eat, the better off you are in all aspects of health.  Fiber is never a wrong answer, but meat does play a role in heath.  How you prepare it may influence your risk of colon cancer. Charred meats contain harmful chemicals that can influence colon cancer growth.  Cook your meat, but don’t overcook it.  The chemicals in processed meats are also bad for us.  It is better to find meats that are natural.  I am unaware of any exercise study that would give you an amount or activity recommendation, but again, more is better than less and some is better than none.

   You may have noticed that clinics are persistent in pushing screening.  Screening for colon cancer, and many other health conditions, have become known as quality measures.  The percentage of patients that are screened is a measure of the “quality of the clinic.”  The clinics are incentivized to get some form of screening done.  The more screening that is done, the more they get reimbursed from the insurance company, or the less that is withheld from the provider’s paycheck.  While I still believe in screening for a variety of health conditions, this approach does bother me.  I feel that patient autonomy should be valued most.  It is your right to decline.  In the end, it is up to you as to which, if any, screening that you go through.

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