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Colon Screening

We are all told we need one to ensure we don't have colon cancer. But, why did we choose this cancer to look for instead of ovarian or pancreatic which are far more deadly when discovered? It is based primarily on frequency. How common are these cancers? How common a cancer is we call 'incidence'.

Why Screening?

Colon--Approximately 4.4% of men (1 in 23) and 4.1% of women (1 in 25) will be diagnosed with colon cancer in their lifetime.

Pancreas--1.7% for both men and women in their lifetime

Ovarian--1.3% lifetime


Other reasons for choosing colon cancer to screen for, is that the screening can be done at longer intervals because colon cancer tends to grow much more slowly. AND, there is good treatment.

When to start?

For years we were told at age 50. In fact, it seemed to become a joke about what you could look forward to when you reached that milestone. However, in a large review from 2016 the United States Preventative Services Task Force is now recommending screening beginning at age 45. I would like to briefly go over these statistics--which is why I tend to recommend Fecal occult testing or Cologuard between 45 and 50 and then colonoscopy after age 50, "If screening were performed from ages 45 to 75 and estimated 50 cases of Colon cancer would be averted and an estimate 25 deaths per 1,000 people screened. This translates to an estimated 110 additional days of life per person screened.

By lowering from 50 to 45 years, we gain an additional 3 cases of cancer found and 1 more death averted and an additional 8 to 10 days of life per person screened.

The three major tests performed. Note. CT scans are NOT typically used as screening tools. Simply put, imaging has a difficult time telling the difference between stool and cancer.

Comparing how well they work. We talk often about 'sensitivity'--The ability to detect the disease that is actually present. Meaning. If you have a 100 people who HAVE colon cancer, what number out of a hundred does your test detect.

1. Colonoscopy--The "Gold Standard" This is typically done every 5-10 years --95% sensitive
2. Cologuard test (I call this the poop in a bucket test) This is typically done every 3 years--92% sensitive
3. Fecal occult blood test (wiping stool on a card) This needs to be done every year --74% sensitive


Advantages of Cologuard and Occult blood testing is that they can be done at home and don’t require preparation nor sedation.

The Facts

The prep. It matters. A lot. In fact, roughly 20-25% of preps are inadequate.  Which often means things can be missed which leads to ‘you need to return sooner’ perhaps in only 3 years.  In other words, the safest prep with the most efficacy still tends to be the Polyethylene glycol with the most volume (4 liters—yep, that’s about 1 gallon).  The good news is that it is a great conversation starter at parties!



Sedation—You don’t actually have to be sedated.  Though I think this is a lot how women think of childbirth, ‘if you can choose sedation, why wouldn’t you?’  Having said that, I have had several patients do it without sedation (most famously was Katie Couric on live TV) and said it wasn’t that bad. 



Polyps—What you might read about in your report


--Hyperplastic polyps.  Typically, < 5 mm. in size.  These are the most common non-cancerous polyps.  If < 10 mm. follow up typically in 10 years.  If > 10 mm. f/u in 3-5 years. 


--Sessile serrated polyps.  These polyps can show signs of dysplasia and potentially become cancerous.  Even those < 10 mm. the recommendation is typically to follow up in 3-5 years. 


--Adenomatous polyps are the most common potentially cancerous polyps (which isn’t to say that all adenomas are cancerous)  In fact, 25 to 30 % of all colonoscopies will show at least one adenomatous polyp at age 50.  In general, follow up for adenomas is a complicated algorithm but most would be between 1 and 5 years. 

They are classified as either:  Tubular, Villous or Tubulovillous

   And as either with Low Grade or High Grade dysplasia


What tends to be concerning in an adenoma are any of these characteristics:

    --Villous Adenomas

    --Greater than 10 mm. in size

    --High Grade dysplasia

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