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Preventing colon cancer through the use of NBI with magnification.

I am an endoscopist. You can define endoscopists as “stupid” doctors who only trust what they can see. In endoscopy, only seeing is believing.

 

A common procedure I perform is colonoscopy, which is an endoscopic exploration of the colon. Why do we do colonoscopy? Firstly, to find out if there is any colon cancer, and secondly, to look for and remove polyps. A polyp is a small lesion in the colon that usually looks like a small hump. Certain types of polyp have to be removed; others you can just leave.

 

How can you differentiate between polyps that need to be removed and those that don’t? The answer is to use NBI with magnification. NBI stands for narrow band imaging, a standard addition to an endoscope. It’s nothing new; I have been using this for more than 10 years in my home country, Japan. We use NBI with magnification so that we don’t miss lesions, and so that we can evaluate a lesion on the spot.

 

Unfortunately, many endoscopes used in this country are not up-to-date. Simply put, if you visit an endoscopist here, it’s most likely that the endoscope will be backward and out of date.

 

The Right Training

 

There are different levels of institutes providing medical services: university hospitals, large hospitals, and then clinics. In many places, NBI with magnification is available in clinics. Here, such equipment is limited to the university hospital level. Beyond that, having modern equipment does not ensure the quality of the procedure.

 

Endoscopists need training. While some larger hospitals do invest in training their endoscopists, a short period of study is not enough. When I began my studies, we already had this equipment; I used NBI with magnification from the beginning. If you have it, it takes half a second to know whether or not a polyp needs to be removed.

 

Polyp Removal and Preventing Cancer

 

Quite often when a patient comes to me for a colonoscopy, it’s not their first time. I’m often told that in a previous procedure, the doctor removed a polyp, which was benign. My question is, was it a hyperplastic polyp, or was it an adenoma? As I said, when you find a polyp, there is a type that should be removed, and there is a type that you shouldn’t touch. An adenoma should be removed; a hyperplastic polyp won’t bother you.

 

Adenomas are a precursor to cancer. They are considered precancerous lesions. That’s why when we find one, we remove it. Hyperplastic polyps are completely unrelated and pose no threat at all.

 

When seen through an older endoscope, both kinds of lesions look identical except to the most highly-trained endoscopists. But NBI clearly reveals the reticular vessels in adenomas. There are also colon cancers called de novo, which start as cancer without going through an adenoma stage, but these are relatively rare.

 

If you find an adenoma larger than 10mm, there is a 5% chance that there are already cancer cells in it. That’s the reason we remove adenomas when we find them. Of course, there are borderline cases, and not every adenoma will become cancerous. But if you can prevent cancer, why wouldn’t you?

A hyperplastic polyp: a lesion in the colon that doesn't cause cancer. Photo by Dr. Okuda.


An adenoma. These polyps are often cancerous and need to be removed. Photo by Dr. Okuda.


Potential Problems

 

As an endoscopist, I don’t feel good performing an unnecessary procedure. There is always a risk when removing a polyp of any kind. In a very small percentage of cases, there can be rupture of the colon or excessive bleeding, despite the fact that it’s a simple procedure.

 

One of my patients told me that in their previous colonoscopy, 10 polyps were removed. When I checked the pathology report, I saw they were all hyperplastic polyps. If removal is unnecessary, best avoid it. But even if there are 10 polyps and nine are hyperplastic, I wouldn’t want to miss that one adenoma. By using NBI with magnification, you can avoid removing the majority of hyperplastic polyps with confidence.

 

Patients should know how to ask the doctor if the endoscope being used is up to standard. The simplest question to find out whether or not the hospital, institute or doctor has up-to-date equipment is, do you have NBI with magnification?

 

If you do colonoscopy regularly after specific intervals, you can greatly reduce the risk of colon cancer by finding and removing adenomas. Certain people have a predisposition to developing an adenoma; usually those people will have a family history of colon cancer at a young age (under 50). My recommendation is that if your previous procedure found an adenoma, you should have another check in two years’ time.

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