What is colorectal cancer?
Colorectal cancer is the cancer of the colon (large intestine) and rectum (last 15cm of the large intestine before the anus).
Risk factors for colorectal cancer
Factors that can increase your risks of colorectal cancer include:
- Older age
- Personal history of colorectal cancer or polyps
- Personal history of inflammatory bowel disease such as ulcerative colitis and Crohn’s disease
- Personal history of radiation therapy
- Family history of colorectal cancer
- Inherited syndromes such as familial adenomatous polyposis (FAP) and Lynch syndrome, otherwise known as hereditary nonpolyposis colorectal cancer (HNPCC)
- Alcohol consumption
- Sedentary lifestyle
- Low-fibre, high-fat diet
Symptoms of colorectal cancer
Colorectal cancer is asymptomatic in its early stages. Symptoms of the disease will vary based on how big the tumour is, its location and the stage of the disease.
General symptoms include:
- Significant change in your bowel habits
- Bleeding from the anus
- Blood in your stool (bright/dark red or occasionally appearing ‘blackish’)
- Persistent pain in the abdomen
- Loss of appetite
- Persistent lethargy and looking pale or jaundiced
- Unexplained weight loss
How does colorectal cancer start?
The vast majority of colorectal cancers begin as a growth known as polyps within the colon and rectum. If these are not removed, they can grow and develop into a cancerous tumour over time.
How does colorectal cancer spread?
If a cancer is left unchecked, the cancer cells will grow and invade into blood vessels, lymph nodes and nearby organs. Left untreated, these will eventually travel to the other distant organs such as the liver and lungs.
What happens after colorectal cancer has been diagnosed?
After colorectal cancer has been confirmed, further tests to determine the stage of the disease will be ordered by your doctor. This can comprise of blood tests, PET-CT scans, MRI scans, ultrasound scans and further biopsies to obtain tissue samples.
Treatment for colorectal cancer
Treatment usually involves surgery to remove the cancer. Other treatments such as chemotherapy and/or radiation therapy may also be recommended. Treatment modalities are individualised for the patient depending on the stage of the cancer, location of the tumour and other health concerns.
Surgery for early stage colorectal cancer
If the tumour is small, a minimally invasive approach to surgery can be performed. This includes:
If the cancer in the polyp is small, it may be possible for your doctor to completely remove the polyp during a colonoscopy.
Endoscopic mucosal resection
For larger polyps, complete removal of the polyp may be performed with a portion of the inner lining of the colon.
Transanal minimally invasive surgery (TAMIS)
This is a specialised minimally invasive surgical approach used to remove large polyps and early cancers within the rectum. It is considered an organ-sparing operation performed entirely through the body’s natural opening (the anus). Unlike traditional surgery, only diseased tissues with clear margins are removed leaving the rest of the normal intestine intact.
Laparoscopic / keyhole surgery
This is a form of minimally invasive surgery, and can be used for tumours that cannot be removed during a colonoscopy. In this operation, your surgeon will make several small incisions in your abdominal wall for the insertion of special cameras and instruments to perform the operation of removing a segment of large intestine together with lymph nodes. As the incisions are smaller, there is less pain, recovery is quicker and there are fewer post-operative complications.
This is another form of minimally invasive surgery that uses small incisions, a camera and surgical instrument. From a surgical console, your surgeon will perform your surgery using various surgical instruments attached to robotic arms. Besides high definition views, the console provides your surgeon with magnified 3D video images, which allow for increased surgical precision. The robotic arms are more ergonomic, with an increased range of motion within a small space, providing greater accuracy which can lead to less surgical trauma, bleeding and post-operative pain.
Surgery for advanced colorectal cancer
In more advanced colorectal cancer cases where the tumour is large, causing blockage or invading into surrounding organs, minimally invasive methods cannot be used. In these cases, open surgery would be required to treat the disease.
A large incision is made in the abdomen. Your surgeon will use surgical instruments to proceed with the operation to remove the cancer and the involved organs. With a larger incision, the hospital stay will be a few days more compared to minimally invasive surgical approach.
Tumours in the colon and rectum can grow to a size that can cause obstruction to the passage of faeces. Stomas may be required in emergency operations or conditions which preclude with patient from a major surgery such as medical conditions or advanced disease.
A stoma is a surgically created opening in the small or large intestinal which is then brought out to the abdominal wall and stitched to the skin. A bag is attached around the stoma to the abdominal wall for collection of the intestinal contents. The stoma may be temporary to allow for diversion of faecal contents or be permanent in nature.
Screening for colorectal cancer
Did you know that colorectal cancer is the most common cancer in Singapore and is increasingly affecting populations in Asian countries?
Although older adults are more likely to develop this type of cancer, there is an increasing number of adults below the age of 50 being afflicted with this condition.
Removing a polyp can prevent a cancer from occurring. Finding colorectal cancer at its earliest stage through a colonoscopy provides the greatest chance for a cure.
These polyps or early cancers are difficult to detect without proper screening as they do not cause you to exhibit any symptoms when they are small. Hence, for the average risk individual, it is recommended that you go for frequent screening colonoscopy to help detect polyps and cancer early, especially if you are 50 years and older.
To learn more about colorectal cancer or to arrange for a screening, make an appointment with a specialist.
Article reviewed by Dr Jonathan Foo, general surgeon at Mount Elizabeth Hospitals
Colorectal Cancer: Get the Facts. Retrieved on 19/06/2019 https://www.healthline.com/health/colorectal-cancer/colorectal-cancer
Christian Nordqvist (09/01/2019) Colorectal cancer: What you need to know. Retrieved on 19/06/2019 https://www.medicalnewstoday.com/articles/155598.php
Colon cancer. Retrieved on 19/06/2019 https://www.mayoclinic.org/diseases-conditions/colon-cancer/symptoms-causes/syc-20353669
Surgery for Colon Cancer. Retrieved on 19/06/2019 https://www.cancer.org/cancer/colon-rectal-cancer/treating/colon-surgery.html