Colorectal cancer is the 6th most common cause of cancer death in India and starts in the large intestine (colon) or rectum. It occurs when cells in the colon go out of control and mostly in older adults (above 45 years). This type of cancer usually begins as small benign clumps of cells called polyps which form inside the colon region and after some time these polyps become cancer cells. The healthy cells in the colon develop mutations in their DNA and accumulate together to form a tumour. Over time these cancer cells grow to invade and destroy the normal tissue nearby.
While there is no specific cause behind the development of colorectal cancer and most are found among people without a family history of colorectal cancer. However, approximately 1 in 3 people who are affected by the condition have other family members (parent, sibling, or child) who have suffered from colorectal cancer.
This puts people with a history of colorectal cancer at increased risk. The reasons for the increased risk are not clear in all cases but it is higher if their relative was diagnosed with cancer before 50 years or if more than one parent, sibling or child is affected. If you also have family members who have had adenomatous polyps or have a history of adenomatous polyps then you must speak to your doctor and check with them on the need to start screening before the age of 45. Screening helps in detecting this cancer early and therefore if you have had colorectal cancer then you must inform your close relative so they can start their screening at the right age.
Colorectal cancer presents several symptoms and risk factors which can help in identifying it early. These include –
- Constant changes in bowel habits diarrhoea or constipation and modifications in stool
- Blood or rectal bleeding stool
- Persistent discomfort in the abdomen such as cramps, gas or pain
- Fatigue or weight loss
- The symptoms of Colorectal cancer vary from patient to patient in terms of size, and location in the large intestine. Several people with colon cancer do not experience any symptoms in the early stages of the disease.
Old age – While colon cancer can be diagnosed at any age but it is mostly found in people above the age of 50 years. There is no specific cause behind the diagnosis as the number is also increasing among young people.
Personal History – If you have already had colon cancer or non-cancerous polyps then you are at a greater risk of getting colon cancer in future.
Inflammatory intestinal conditions – It includes diseases like Crohn’s disease and ulcerative colitis that can increase your risk of colon cancer.
Inherited Syndromes – A very small percentage of colon cancers are caused due to inherited syndromes like Familial Adenomatous Polyposis (FAP), and Lynch syndrome, which is also known as Hereditary Nonpolyposis Colorectal Cancer (HNPCC).
Family History – The risk of Colorectal cancer increases if you have a blood relative who has had the disease. If more than one family member has colon cancer then the risk is even greater.
Sedentary Lifestyle – People who are inactive or adopt a high-fat or low-fibre diet are at an increased risk of colon cancer. Alcohol consumption and heavy smoking put you at higher risk. Following a healthy lifestyle and getting regular physical activity can reduce your risk.
Type 2 Diabetes – Patients with type 2 diabetes (non-insulin-dependent) have an increased risk of colorectal cancer.
Obesity – People who are obese are at increased risk and have less favourable outcomes compared to people with normal weight.
Radiation therapy – This therapy when directed towards the abdomen to treat previous cancers increases the risk of colon cancer
How can you prevent yourself from colon cancer?
There are several precautionary measures that you can adopt to prevent yourself from colon cancer –
Screening – Colon cancer screening through traditional colonoscopy every 10 years after the age of 45 is recommended before any signs or symptoms may develop. Doctors also include several other tests that include –
Colonoscopy – It is a type of screening where a colonoscope is used to gain images of the colon and rectum. This method is considered the “gold standard” in colon cancer screening because of its accuracy and the ability of your doctor to remove the growths at the same time.
Virtual/CT colonoscopy – In this method the doctors use computed tomography (CT) scans once the colon is slightly inflated to provide clearer images
Flexible sigmoidoscopy – This uses a light and camera lens or a sigmoidoscope to view the colon
Fecal occult blood test (FOBT) – This screening method uses a light and camera lens or a sigmoidoscope to examine the colon. With this test, the doctors can find microscopic traces of blood that may not be visible during a normal bowel movement at home.
DNA stool test – This helps in analyzing a stool sample for any genetic changes that can indicate colorectal cancer.
Lifestyle changes – Moderating your alcohol consumption, curbing smoking, maintaining a healthy weight and regular exercise are some preventive measures through which you can reduce your risk of colon cancer.
Authored by Dr. Vijay Agarwal, Lead & Sr. Consultant – Medical Oncology & Haematology, Aster CMI Hospital, Bangalore