What is Colorectal Cancer?
Cancer is the uncontrolled division of abnormal cells. Colorectal cancer (bowel cancer) occurs in the colon or the rectum, the major parts of the large intestine that function to store and expel waste products of digested food. Most colorectal cancer begins as a mass of abnormal cells called a polyp. Untreated polyps can spread into nearby tissues, lymph nodes or distant organs (later stages), disrupting their function. Although colorectal cancer affects people of all ages, it is common in people aged 60 and above. It is one of the leading causes of cancer death among men and women.
Types of Colorectal Polyps
There are two types of colorectal polyps:
- Hyperplastic Polyps: These are benign polyps that grow with the help of a stalk. Polyps that are large in size or number may increase your risk of colon cancer.
- Adenomatous Polyps: These are gland-like growths and are considered pre-cancerous since most of them go on to become cancer.
Stages of Colorectal Cancer
Colorectal cancer progresses from stage 1 to stage 4 as follows:
- Stage I: Tumour penetrates the mucous layer of your colon or rectum
- Stage II: Tumour spreads to the wall of the intestine
- Stage III: Cancer has moved to a nearby lymph node
- Stage IV: Cancer has spread to distant organs of the body
The common risk factors of colorectal cancer include:
- Consuming excess alcohol
- Being obese
- Having type II diabetes
- Physical inactivity
- Advanced age
- Family history of colorectal cancer
Symptoms vary depending on the stage of cancer. You may experience some of the common symptoms including:
- Stomach pain
- Nausea and vomiting
- Blood in the stool
- Unusual weight loss
- Weakness and fatigue
- Abdominal bloating and cramping
The diagnosis of colorectal cancer may be made via the following:
- Colonoscopy: A procedure done to look inside the entire colon. It is performed using an instrument called a colonoscope, a flexible tube with a tiny camera attached to one end which is connected to a large screen.
- Sigmoidoscopy: This is performed to examine the large bowel and the rectum using a sigmoidoscope (another flexible tube similar to the colonoscope).
- Barium enema: In this procedure, barium fluid is administered into the bowel through the rectum. X-ray images are then captured to view the inside of the bowel to detect any abnormalities.
If colon cancer is confirmed, staging is performed to detect the size, location, and advancement of the cancer. Staging is performed using ultrasound or computed tomography (CT) scanning of the abdomen, chest X-ray, magnetic resonance imaging (MRI) scans of the bowel, and a blood test called a complete blood count (CBC).
Treatment depends on the stage of colorectal cancer and can involve one or more of the following treatment options:
The use of drugs to treat colorectal cancer. The drugs may be pills or intravenous injections.
High-energy particles or waves such as X-rays and gamma rays are used to kill or damage cancerous cells.
Targeted Cell Therapy
This involves the use of drugs that specifically target certain proteins in cancer cells to destroy them, but do not damage the other cells of the body.
A healthy immune system is necessary to fight cancerous cells. Biological therapy involves administering interleukins or interferons (types of proteins) to naturally defend your body against cancerous cells.
Colectomy and Proctectomy
Colectomy is a common procedure performed to remove the cancer cells. It is the surgical resection (removal) of all or part of the large intestine. It is also called a large bowel resection. Proctectomy is the surgical removal of all or part of the rectum. Colectomy or Proctectomy is performed under general anaesthesia by an open-surgery method or by laparoscopic method. Laparoscopy is a minimally-invasive surgical procedure that uses a laparoscope to diagnose and treat various disorders. A laparoscope is a thin fibre-optic device fitted with a camera and lens. Images from the camera are transmitted to a monitor for your doctor to view the inside of your body.
A person with rectal cancer may require a colostomy. An opening called a stoma is created by your surgeon on the outside of your body, through which faeces pass to be collected into a colostomy bag.