A Guide to Colorectal Cancer: Risks, Screening, and Treatment Options

Understanding Colorectal Cancer

Colorectal cancer can also be called colon cancer or rectal cancer, depending on where it starts. However, colon cancer and rectal cancer are often categorised together due to their similarities in characteristics. Its common types include:

• Adenocarcinoma: The most common type is adenocarcinoma, which makes up about 96% of colorectal cancers. It originates in cells responsible for producing mucus, serving to lubricate the interior of the colon and rectum.
• Gastrointestinal Carcinoid Tumour: This tumour starts in the hormone-producing cells in the intestine. It is usually slow-growing and less aggressive than adenocarcinomas.
• Gastrointestinal Stromal Tumour (GIST): Though more prevalent in other digestive tract regions, GISTs can also develop in the colon. They originate from specialised cells in the gastrointestinal tract wall, called Interstitial Cells of Cajal.
• Lymphomas: Lymphomas are cancers that develop in the lymphatic system, a part of the immune system. They typically start in lymph nodes, but they can also begin in the colon, rectum, or other organs.
• Sarcomas: Sarcoma is a type of cancer that originates in the blood vessels, muscle layers, or other connective tissues in the walls of the colon and rectum. Sarcomas of the colon or rectum are rare.

Risk Factors for Colorectal Cancer

Certain risk factors increase an individual's likelihood of developing colorectal cancer. Understanding these risk factors is crucial for the prevention and early detection of this condition.

• Age: Colorectal cancer is more common in people aged 50 or older, but it can occur at any age.
• Smoking: Carcinogens in tobacco smoke directly damage colon cells, which may contribute to the development of cancer.
• Sedentary Lifestyle: Lack of exercise can disrupt hormones and weaken the immune system.
• Chronic Stress: Chronic stress can have adverse effects on the body, such as lowering the immune system and increasing susceptibility to diseases, including cancer.
• Family History: Having a family history of colorectal cancer or certain diseases like diabetes, ulcerative colitis, or Crohn's disease increases the risk of developing colorectal cancer.
• Presence of Polyps in the Colon: Colorectal cancer begins as benign growths known as polyps in the lining of the colon. Over time, some of these polyps can turn into cancer if left untreated.

Screening Methods for Colorectal Cancer

Early detection is key to successful colorectal cancer treatment. Several screening options exist, ranging from convenient at-home tests to more in-depth procedures. Talk to your doctor about your risk factors and which screening method is right for you.

These screening methods include:

• Colonoscopy: This test has a high level of accuracy and can show precisely where a tumour is. It is similar to flexible sigmoidoscopy but involves the use of a longer, thin, flexible, lighted tube to identify and remove polyps or cancer inside the rectum and the entire colon.
• Non-invasive tests: Faecal Occult Blood Testing (FOBT) and Faecal Immunochemical Test (FIT) check for hidden blood in the stool, an early sign of cancer. However, these tests have limitations and may not always catch every case.
• Flexible sigmoidoscopy: It involves using a sigmoidoscope, a flexible tube with a camera, to detect abnormalities such as polyps or signs of cancer. While the preparation is less complicated than a colonoscopy, it is not as thorough in checking for abnormalities because it can only assess the left side of the colon or about a third of it.
• Computed Tomography Colonography: This non-invasive imaging test, also known as virtual colonoscopy, uses X-rays and computers to produce detailed images of the entire colon and rectum. It can detect polyps or signs of cancer without the need for sedation or the insertion of a scope.

Treatment Options for Colorectal Cancer

Colorectal cancer treatment is tailored to each patient’s specific circumstances. Doctors consider several factors, including the stage, location of the tumour, overall health, and individual preferences in determining the best treatment course.

Colorectal surgery is the most common kind of treatment for all stages of colorectal cancer. It can be performed via a traditional open approach, laparoscopically (keyhole), or robotically.

• Local Excision - A minimally invasive option for early-stage cancers, Local excision removes small tumours with a margin of healthy tissue from the colon wall.
• Resection - This surgery removes part of the colon or rectum along with nearby lymph nodes and healthy tissue to prevent cancer spread. The healthy ends of your colon are then sewn back together.

In most cases, colorectal cancer treatment involves a multimodal approach, combining surgical and non-surgical treatments, which include:

• Chemotherapy - Drugs are used to destroy cancer cells and stop them from growing and reproducing throughout the body. This is typically given to patients after surgery to eliminate any remaining cancer cells.
• Radiation Therapy - Using high-energy beans, radiation therapy is often used before surgery to shrink tumours and after surgery to destroy residual cancer cells. In some cases, it may also be used as a complementary treatment to chemotherapy.
• Immunotherapy - This drug-based treatment boosts the body's immune system and helps it detect and destroy cancer cells. Immunotherapy is often given to patients with advanced colorectal cancer.