Colon Cancer Screening in Bangkok, Thailand
Colon cancer begins as a slow-growing, small growth in the colon or rectum area. Over time, these precancerous growths – called polyps – can turn into cancer. Colonoscopy is a screening test that checks the inner lining of the large intestine for polyps. It provides the best diagnostic accuracy of all detection methods and offers the additional benefits of no pain, no incision, and only a short time needed for both preparation and procedure. A colonoscopy will detect most small polyps and almost all large polyps and cancers, thereby substantially reducing the risk of developing and/or dying from colon cancer by up to 90%.
Colonoscopy once every 10 years, for adults above 45, reduces colon cancer mortality by more than half.
Source: American Cancer Society
How does a colonoscopy work?
When looking at the epithelium and the shape of the blood vessels in a polyp, the doctor will check to see whether any abnormalities can be identified. Previously, the doctor would conduct a colonoscopy using a white light, but this method does not always give a clear enough image. In such cases, a dye injection may be administered to the patient to highlight epithelium and the shape of the blood vessels. But the dyeing process takes time to achieve enough contrast for examination.
Subsequently, through a medical collaboration with Sano Hospital in Japan, Samitivej adopted Narrow-Band Imaging (NBI) International Colorectal Endoscopic classification (NICE) with magnification, the most validated classification system for the detection of colorectal polyps. NBI is an imaging technique that uses a light spectrum of blue and green wavelengths to stimulate hemoglobin (Hb) (an important molecule carried by our red blood cells). As the hemoglobin molecules absorb the blue and green wavelengths, nearby blood vessels will start to appear a dark brown in color, which allows us to see the epithelium and shape of the blood vessels more clearly due the contrast in color. NBI also enables us to magnify these images, so that the doctor can see the shape of the blood vessels in maximum detail, and can immediately distinguish the depth of any invasion of cancer cells in the tissue.
The composition of cell tissue in a colorectal polyp, as seen by NBI, can be divided into three types called NICE classification:
NICE 1: The polyp’s cell tissue still has a normal composition. In this case, the doctor will order follow-up checks to monitor the development of the polyp, but will not need to remove the polyp because the chances of it being cancerous are still very slim.
NICE 2: The composition of the cell tissue looks similar to a net, which indicates that the cells could become cancerous in the future. The doctor will therefore remove the polyp immediately using a coil or a special type of electric knife.
NICE 3: The cell tissue appears wild and disorderly, much like cancer cells. In this case, the doctor may not remove the whole polyp using a colonoscope, but may use tissue acquisition instead. A consultation with an oncologist will be needed to assess which method of removing the polyp is most suitable.
The use of the NBI technique gives a more precise diagnosis, and also makes it easier for the doctor to devise a treatment plan. NBI can identify even the smallest polyps, as little as 5mm in diameter, so that the doctor can calculate as accurately as possible whether the polyps pose a risk to the rest of the body. With a white-light colonoscopy, however, such small polyps might go unnoticed. Still, the effectiveness of any colonoscopy using NBI largely depends on the expertise of the doctor and his mastery of the technique, specifically his adeptness at reading the results of the epithelium screening. Moreover, due to there being only a small number of doctors who are experts in this technique, NBI is often overlooked as a screening option. This should not be the case, however, as NBI offers a safe alternative to chromoendoscopy, which requires the patient to be injected with a dye or stain.
How is it done?
- The first step is to clear the bowel using an oral laxative so that is clean, because normally there are faeces remaining inside the bowel at all times. Patients may have to start drinking the laxative at night in preparation for their colonoscopy the next morning. Patients will also need to abstain from eating and drinking for six hours before the screening. Alternatively, patients may abstain from eating and drinking from home and consume 2 – 3 liters of laxative in the morning at the hospital, and spend 2 – 3 hours using the toilet until the bowel is clear and ready to receive the colonoscope.
- Next, the doctor will inject the patient with a sedative and a painkiller, to reduce discomfort caused by distension of the colon when it is filled with air, much like when a balloon is inflated. This should allow the doctor to see the interior of the colon in detail. However, if the patient is elderly and has a chronic illness, he or she will be administered a weaker sedative in the form of an inhalant, one that is fast-acting but wears off quickly.
- Once the patient is sedated, the doctor will insert the colonoscope into the rectum. The colonoscope will be around 1.60m long, so that it can extend the entire length of the bowel, which is around 1.50m long. After inserting the colonoscope, the doctor will then gently guide it deep into the bowel, to a depth of around 70 – 80cm. The doctor may check as far as the entry of colon and the end of the partial small intestine.
- If a polyp smaller than 3cm is detected, the doctor will excise the polyp via the colonoscope. The colonoscope will have a duct through which cauterisation equipment can be inserted for excising outgrowths of tissue. This means that polyp removals can be performed at the time as a regular screening, within a single procedure. The screening process should take about 30 minutes, but may take longer if there are many polyps that require removal.
During colonoscopy, if specialists find large flat polyps, Endoscopic Submucosal Dissection (ESD) technique will be applied to remove polyps without the need for open surgery. This minimizes surgical risks, removes the need for abdominal incisions (scarless), shortens hospitalization, and allows patients to recover much more rapidly. All of this enables patients to return to their normal lifestyle more quickly, reduces complications and increases safety levels. ESD is a new scarless surgical technique implemented by Samtivej Hospital as a results of its collaboration with Sano Hospital, Japan’s leading private hospital specialized and advanced in gastrointestinal (GI) endoscopy for advanced diagnosis and therapeutic via endoscopy.
Who is it for?
According to American Cancer Society, colon cancer screening is recommended for people who are 45 or older and thus at higher risk; however, that does not mean that people younger than 45 have no chance of developing colon cancer. Click here to learn warning signs, symptoms and risk factors.
Colon cancer studies conducted in the United States recommend that patients should undergo a follow-up screening approximately every 10 years. The studies warn, however, that 6 – 8% of patients whose first screening identified interval cancer in a subsequent screening 10 years later. This indicates that, for some patients, one screening every 10 years is too infrequent. Many observers therefore recommend that the interval between each screening should be reduced to seven years or five years, but there is still disagreement on this point. Finding the correct frequency of screenings will depend on the individual profile and symptoms of each patient. Some patients may not need to wait 5 – 10 years, they may need to wait just two years. The doctor will therefore consider each patient on a case-by-case basis.
How to prepare for a colonoscopy?
The first step is to visit a doctor to evaluate your situation and suitability. If you take medications or supplements, inform the doctor as you may need to adjust your dosage or stop the medications until after the colonoscopy.
After making an appointment for your colonoscopy, you should take the following steps:
- Stop taking aspirin or other medications that thin the blood for a week before the colonoscopy.
- Do not eat high-fiber food such as vegetables or fruits three days before the colonoscopy.
- Clean out your entire colon and rectum by taking a laxative and following the preparation procedures provided by your doctor the day before the colonoscopy.
- Do not eat or drink anything at least 6-8 hours before the colonoscopy.
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