Colon cancer occurs in any part of the colon, which is the longest part of the large intestine. The primary function of the colon is to remove water and some nutrients and electrolytes from partially digested food.
Cancer typically develops from polyps that form inside the colon. They aren't usually cancerous, but they can turn into cancer over time. These don't always cause symptoms, which is what makes colon cancer easy to miss, especially during the early stages. Therefore, doctors recommend regular screening.
Also Read: Colorectal Cancer Is The Third Most Common Cancer Worldwide: Expert Shares Tips To Reduce Its Risk
Understanding The Risk Factors For Colon Cancer
While colon cancer can occur in anyone, Dr Devavrat Arya, Senior Director, Medical Oncologist, Max Hospital, Saket, New Delhi, shares that some people may be more at risk of developing the disease than others. These include:
- Age (50 years and older, though screenings are now recommended starting at 45)
- Family history of colon cancer or colorectal polyps
- Genetic syndromes (e.g., Lynch syndrome, familial adenomatous polyposis)
- Personal history of inflammatory bowel disease (e.g., Crohn’s disease, ulcerative colitis)
- Lifestyle factors (e.g., diet high in red or processed meats, physical inactivity, obesity, smoking, heavy alcohol use)
It is important to note that young people too can develop colon cancer, although it is less common, says Dr Arya, adding that risk factors such as a family history of colon cancer, genetic syndromes, and inflammatory bowel diseases can increase the likelihood of developing colon cancer at a younger age.
When Is The Right Time To Get Colon Cancer Screening?
Dr Arya notes that colon cancer screening should start at age 45 for individuals at average risk.
Those with a higher risk, such as a family history of colon cancer, genetic syndromes, or inflammatory bowel disease, may need to begin screening earlier and undergo more frequent screenings, he adds.
Screening Methods For Colon Cancer
Some of the common screening methods for colon cancer include:
Colonoscopy
A flexible tube with a camera is inserted through the rectum to examine the entire colon. This type of test is recommended every 10 years for average-risk individuals starting at age 45.
Flexible sigmoidoscopy
It is similar to a colonoscopy, but a flexible sigmoidoscopy only examines the lower part of the colon. It is recommended every five years, often combined with annual faecal occult blood testing.
Faecal Occult Blood Test (FOBT)
This type of test detects hidden blood in the stool. It is recommended annually. Types include guaiac-based FOBT and the Faecal Immunochemical test (FIT).
Stool DNA test
This test investigates a stool sample for DNA mutations and blood associated with colon cancer and is recommended every three years.
CT colonography
It uses CT scans to create detailed images of the colon and rectum, recommended every five years.
Double-contrast barium enema
An X-ray test where the colon is filled with barium to provide clear images is recommended every five years.
Blood-based CT DNA testing
This process involves drawing blood samples and testing for circulating tumour DNA, thereby enabling early identification of colon cancer and precancerous lesions. A study has shown blood-based cancer screening tests detect 83% of people with colorectal cancer.
Which Is The Preferred Mode Of Screening For Young People?
For young people, especially those without any risk factors, regular screening typically begins at age 45, with colonoscopy being the preferred mode of screening due to its comprehensive nature and ability to detect and remove polyps during the procedure, says Dr Arya.
He adds, “For high-risk young individuals, more frequent and earlier screenings may be necessary, and colonoscopy remains a preferred method due to its effectiveness in early detection and prevention.”