The digestive system, which refers to the gastrointestinal (GI) tract, begins in the mouth and travels throughout the body, including the thorax and abdomen, before exiting at the anus. It is comprised of the oesophagus traversing through the chest and connecting to the stomach, then the intestines, colon, appendix, and rectum. The liver, biliary tract, gallbladder, pancreas, and spleen are located in nearby structures along this course.
Common GI problems and symptoms that bring people to see doctors include food poisoning, nausea, vomiting, passing blood, jaundice, heartburn, indigestion, bloating, abdominal pain, and constipation. If the symptoms persist, recur or cause significant discomfort, please do not hesitate to see a physician. Most gastrointestinal diseases are preventable and treatable. In particular, early detection and treatment can lead to better outcomes.
GI symptoms may or may not be related to cancer. For example, if you see bright red blood in the toilet bowl or when you wipe, it could come from haemorrhoids or colorectal cancer (CRC). Thus, GI investigations, mainly endoscopy, are necessary to distinguish between the two.
Almost all CRCs begin as polyps, benign (non-cancerous) growths in the lining of your colon or rectum. Colonic polyps are usually asymptomatic. Once in a while, they may induce tenesmus, ulcerate, and bleed. Cancer develops when these polyps grow; some cells become cancerous and start to invade surrounding tissue. In Thailand, CRC has now grown to be the fourth most common cancer behind liver, lung and breast cancers, with more than 11,000 new cases per year.
One distinct characteristic of CRC is that it has a long duration of being benign polyps before turning malignant through a multi-step process. This affords ample opportunity to preempt the development of cancer if the polyp is removed at this stage. Because most polyps and early-stage CRCs do not cause symptoms, a colon cancer screening test should begin while you are asymptomatic.
Thus, the procedure called polypectomy that can be performed while having a diagnostic colonoscopy is very useful to prevent CRC development to the later stages that require advanced treatment, including surgery, chemotherapy, and radiation. Once symptomatic, the cancer usually progresses to late stages, invading through the colonic wall, and may spread to lymph nodes, the liver and lungs. Aggressive types of cancer have a faster disease progression. Therefore, colonoscopy with polypectomy is a complete one-stop service to prevent the morbidity and mortality of CRC. Colonoscopy is recommended for any individual at the age of 45 years of age or earlier if that person carries risk factors such as colon, gastric or breast cancer in the family.
In addition, the following risk factors increase your chances of having colon cancer:
- A diet high in red, processed or grilled and charred meat
- Obesity, particularly those with excess abdominal visceral fat.
- Drinking too much alcohol
- Age is another major risk factor, increasing significantly from the age of 60
- Family history of CRC in a first degree relative
CRC can be easily cured if found and treated in its early stages. One of the most effective methods for detecting colorectal cancer is colonoscopy. The colonoscope, fitted with a tiny video camera and a light source at its tip, allows doctors to inspect the internal lining of the entire colon. If a suspicious lesion is found, a special cutting instrument can be inserted through a small channel in the endoscope to take tissue samples (biopsies). If a polyp is found, it can be removed in the same setting. Most polyps rest on a thin stalk and could be easily removed with a thin electric wire loop called a snare, literally nipping cancer in the bud. The procedure typically lasts 30–60 minutes. It is done under moderate sedation; you will sleep through the procedure without feeling any discomfort.
A colonoscopy is recommended for:
- Investigating intestinal signs and symptoms: A diagnostic procedure to delineate the causes of abdominal pain, rectal bleeding, chronic diarrhea, and other intestinal problems.
- Screening for colon cancer: Adults with an average risk of CRC beginning at age 45 or sooner in high-risk groups.
- Looking for more polyps: Periodic follow-up colonoscopy is recommended for patients who have had polyps removed previously. New polyps, if found, could be removed, forestalling CRC development.
- Treating a clinical condition: Sometimes a colonoscopy may be done for therapeutic purposes.
You need to clean out your colon in preparation for a colonoscopy. Any retained faeces in the colon makes it difficult to get a good view of your colon and rectum and may obscure a lesion. One small 1 cm polyp containing cancer cells reduces the benefit of colonoscopy and you may need to have a repeat colonoscopy sooner than those with a clear colon.
To empty your colon, your physician may ask you to:
- Follow a special diet the day before the exam. Typically, you will be required not to eat solid food the day before the exam. Fluid intake may be limited to clear liquids.
- Take a laxative. Your doctor will usually prescribe a liquid laxative in large volumes (2-4 L).
- Adjust your medication. Notify your doctor of your usual medications at least a week before the exam; certain medications may need to be temporarily withheld.
What to expect post procedure
It takes about an hour to recover from the sedative given during the colonoscopy procedure. It is not safe to drive during the first 24 hours. Have someone take you home because it can take up to a full day for the sedative to completely wear off. You may feel bloated or pass gas for a few hours after the exam as your bowel expels residual gas insufflated into the colon during the procedure. Walking may help relieve any bowel discomfort. If your doctor removes a polyp during the colonoscopy, you may be advised to temporarily follow a special diet and refrain from taking blood-thinning agents for a few days.
Things you can do to prevent GI problems and lower the risk of developing CRC.
- Avoid excessive red meat consumption that may trigger CRC development.
- Add more fruits, vegetables, and fiber to your diet and eat less animal meat and fat.
- Exercise regularly, even moderate regular physical activity is beneficial.
- Maintain a healthy weight. Obesity is an important risk factor for colon cancer.
However, these may not be sufficient to entirely prevent CRC. Thus, a colonoscopy for CRC screening is necessary, starting after you turn 45.
Through colonoscopy, it is possible to prevent, detect, and treat diseases long before symptoms appear. Almost all precancerous polyps can be removed painlessly through a colonoscope. Colonoscopy can detect any abnormal mucosal lesions in the colon, such as polyps, masses, ulcers, colitis, diverticulum, abnormal vessels, and infection/inflammation. Early-stage CRC can also be completely removed by endoscopic techniques. If not caught in the early stages, CRC can spread throughout the body. Advanced cancer requires more complicated surgical operations and medical therapies. Patients diagnosed at a localized or early stage have a much higher chance of cure compared with those diagnosed with late-stage cancer or metastatic spread at the time of diagnosis. Early detection gives the best chance for a cure.
Author: Prof. Dr. Rungsun Rerknimitr (MD), Gastroenterology, American Board of Internal Medicine, American Board of Gastroenterology. Med Park Hospital.
Series Editor: Katalya Bruton, Healthcare Content Editor and Director, Dataconsult Ltd, Dataconsult’s Thailand Regional Forum provides seminars and extensive documentation to update business on future trends in Thailand and in the Mekong Region.