An Overview of Colorectal Cancer
With about 1500 newly diagnosed cases of Colorectal cancer in Singapore each year, the risk of a person getting colorectal cancer during his lifetime is 5.6%. Colorectal cancer comes out to be the most common cancer when considering both the male and female populations in Singapore. It is also the second leading cause of death in the USA.
What is Colorectal Cancer?
The term Colorectal Cancer refers to the cancer of parts of the large gut. i.e., either the colon or rectum. The colon and rectum make up the majority of the large gut. This cancer is most often characterized by the uncontrolled growth of the cells of the large gut lining known as epithelial cells.
Colorectal cancer is strongly linked to family history as well as other gastrointestinal disorders of the large gut such as colonic polyps. Polyps are the outgrowth in the inner lining of the large gut. In fact, most colorectal cancers start as polyps which then acquire the ability to divide indefinitely.
Colorectal cancer may grow outward into the wall of the gut and involve the outer layers from which it can spread to blood vessels or lymph nodes and ultimately to the other parts of the body.
What are the Signs and Symptoms of Colorectal Cancer?
Colorectal cancer in its early stages may be undetected due to being silent (having no symptoms at all) although there are certain alarming signs of colorectal cancer. These include;
● Change in Bowel habits – Colorectal cancer might manifest as diarrhoea or constipation.
● Unexplained Anaemia – When detected on routine investigation might warrant screening for colorectal cancer.
● Blood in stools – Most often presenting as fresh blood mixed with stools.
● Anorexia and weight loss.
● Abdominal Mass – Manifesting as abdominal fullness and other mass effects.
● Abdominal Pain – Most often in the lower abdomen.
Clinically your physician may feel a mass on examination. The diagnosis of colorectal cancer is usually made after a colonoscopy either as a part of screening or on the doctor’s advice. A biopsy Is usually taken during colonoscopy for histopathological testing. A CT scan as well as a barium enema might be done to demarcate the extent of the spread of colorectal cancer.
What are the Risk Factors and Causes of Colorectal Cancer?
The risk factors of colorectal cancer include;
• Having inflammatory bowel disease (IBD).
• Being obese or overweight (Obesity is especially linked to colorectal cancer in men).
• A diet containing a greater amount of red meat or processed meat.
• Having low levels of Vitamin D.
• Sedentary lifestyle (limited physical activity).
• Alcohol consumption.
• Being older than 50.
• Family history of colorectal cancer or having adenomatous polyp of the colon.
• Having type 2 diabetes.
The causes of colorectal cancer are a bit unclear. It is shown to develop from a number of environmental as well as genetic factors.
According to the American Cancer Society (ACS), about 15% of colorectal cancers have been shown to have a strong genetic root. Some inherited genetic syndromes that predispose to colorectal cancer are;
• Familial Adenomatous Polyposis (FAP).
• Hereditary non-Polyposis colorectal cancer (HNPCC).
• Peutz-Jeghers Syndrome.
• MUTYH-associated polyposis (MAP).
Colorectal cancer may result from acquired genetic mutations as well. These involve DNA damage to the patient throughout his/her life. Certain risk factors play a role in these acquired mutations but the exact causes have not been determined yet.
How to prevent Colorectal Cancer?
Some of the preventive measures against the development of colorectal cancer are;
• Screening for colorectal cancer – Regular screening can decrease the risk of the development of colorectal cancer. Polyps if found can be removed if indicated to prevent their transformation into malignant masses. Patients should have a colonoscopy every 10 years starting at the age of 50 years as routine screening. Those having a familial history of colorectal cancer or polyposis may start screening 10 years earlier than the age at which their family member developed the disease or the age of 40 years, whichever comes earlier.
• Dietary measures – Diets having a high content of fruits, vegetables, and whole grains are linked with prevention against the development of colorectal cancer.
• Regular physical activity – Increased physical activity has been linked to a lower risk of colorectal cancer and polyps while limiting the sitting time as well as time lying down also helps in prevention.
• Limiting alcohol intake – Several studies have found an increased incidence of colorectal cancer with increased alcohol intake.
• Maintain Bodyweight at healthy levels.
• Cessation of smoking.
• Taking multivitamins – Some studies suggest a reduced incidence of colorectal cancer with regular intake of multivitamins, calcium and magnesium.