Colonoscopy’s Leading Role in Cancer Prevention & Early Detection

September 17, 2019
Colon and rectal cancer, together called colorectal cancer, are the third-most prevalent cancer worldwide, and the fourth-leading cause of cancer-related deaths. By 2030, new cases are projected to grow 60%, to more than 2 million each year, and the number of people who die from the disease is expected to reach 1.1 million annually.
 
It is estimated that nearly 60% of colon cancer deaths could be prevented with regular screenings including colonoscopy, the leading screening test for the prevention and early detection of colon cancer. In fact, countries where the use of colonoscopies and other colon cancer screenings has increased have seen a decline in the rate of colon cancer.
 
Here are five facts that help explain colonoscopy’s leading role in prevention and early detection of colon cancer.

1. Early detection has life-saving benefits.
Colon cancer is highly treatable and survivable when diagnosed and treated in its early stage. The challenge for early detection stems from the fact that colon cancer, which tends to grow slowly, often does not produce any symptoms until the disease has already progressed to its later stage. At that point, symptoms of colon cancer in both men and women may include:
  • abdominal pain
  • bloating, cramping
  • bloody stools
  • change in bowel habits
  • constipation
  • fatigue
  • feeling that the bowels are never empty
  • nausea and/or vomiting
  • rectal pain
  • unexplained weight loss

2. Colonoscopy is the gold standard of screening tests.
Colonoscopy is the most sensitive screening test for colon cancer. Undergoing a colonoscopy has been associated with the largest reduction in mortality risk of all colon cancer screening methods. There are other alternatives to colonoscopy, though they are more limited in their ability to detect cancerous polyps. Options include:
  • Sigmoidoscopy is a procedure where a doctor inserts a tube smaller in length than a colonoscope through the anus to the lower part of the colon to look for the presence of polyps, abnormalities and cancer. Using this method, the doctor can cut any abnormal polyps and extract them for further examination. Sigmoidoscopy screening is associated with a smaller reduction in colon cancer mortality risk compared to colonoscopy.
 
  • Fecal Occult Blood Testing (FOBT) looks for the presence of polyp or cancer cells. Doctors usually recommend repeating FOBT screening at yearly intervals, which has been shown to reduce one’s colon cancer mortality risk. By contrast, biennial (every 2 years) FOBT screening reduces colon cancer mortality by a more modest amount.
 
3. Colonoscopy serves two purposes.
Unlike other colon cancer screening tests, such as CT colonography and stool tests, colonoscopy is first a diagnostic tool that is highly accurate in identifying polyps and abnormal tissue growths. During the colonoscopy, if a polyp is found, the colonoscopy serves a second purpose — immediate removal of the polyp, a procedure called a polypectomy, with the use of a wire-loop tool inserted through the colonoscope.
 
Early-stage cancerous growths found during a colonoscopy screening can usually be removed during the procedure. As long as all of the cancerous tissue is successfully removed, the patient typically would not require further treatment such as chemotherapy or radiation — a follow-up colonoscopy around 6 months to a year later would check for any signs of recurrence of the cancer.
 
4. Colon cancer usually begins with polyps.
Some types of polyps are highly benign, with the chance of becoming cancer being very low. For other types of polyps, the chance of cancer is high; these types of polyps would be termed pre-cancer or adenomas. Although most polyps do not eventually develop into cancer, nearly all colorectal cancers result from polyps. Some people may have a genetic pre-disposition to colon polyps, while others may be related to lifestyle factors, other chronic health problems, or unexplained causes. Colonoscopy is the method-of-choice for detecting colon cancer and removing any adenomas.
 
5. Be aware of alarm symptoms requiring urgent attention.
Certain symptoms, so-called alarm symptoms, may be a sign of a serious problem requiring urgent medical care. These include: rectal bleeding; continuing abdominal pain and discomfort that does not resolve on its own; an unintentional weight loss of 10 pounds or more; or a change in normal bowel habits, for example, if your regular habit of every 2 to 3 days changes to every 4 to 5 days.
 
Screening Recommendations
It is recommended that men and women with no specific risk factors for colorectal cancer should have a colonoscopy screening around age 50. If you have a family history of cancer or another risk factor for colon cancer or rectal cancer, you are advised to undergo a first colonoscopy screening around age 40. If the screening finds no signs of polyps or pre-cancer indications, then the next screening should follow in 5 to 10 years or as advised by your doctor. If you have questions about whether or when you should have a colonoscopy screening, talk to your doctor.
 

 
By Dr. Veerakit Apiratprachasin, specialist in Gastroenterology and Hepatology at the  
Digestive Disease Center, Bumrungrad International Hospital
 

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