Colon Cancer

Colon Cancer and Rectal Cancer (Colorectal cancer for short)

Are you experiencing bleeding when you pass motion? Change in bowel habit, abdominal pain, loss of appetite or even unintentional weight loss? You need to make sure it is not because of colorectal cancer.

What is the colon and rectum?

The colon and the rectum together form what is commonly called the large intestine, which is the last part of the digestive tract. The large intestine is about 1.4 to 1.6 metres long. The colon is the part which serves to absorb water from the digested food, which enters it from the small intestine. The rectum, which is just above the anus, serves to hold what is not absorbed, which subsequently forms the faeces. From the rectum, the faeces is then expelled through the anus.

What is colorectal cancer?

Colorectal cancer refers to cancer of the cells of the inner lining of the colon or rectum. The medically scientific term is colorectal adenocarcinoma. Most colorectal cancer begins as a small non-cancerous growth called a polyp. If undetected, such polyps can grow and mutate to transform into a cancer. If the cancer is in the colon, it is called colon cancer. If in the rectum, it is called rectal cancer.


Colorectal cancer is the number 1 cancer in Singapore. Amongst males, it is the most common cancer. Amongst females, it is the second most common, after breast cancer.


What are the risk factors of developing colorectal cancer?

  • Family history of colorectal cancer
  • Personal history of polyps or colorectal cancer
  • Smoking
  • Obesity
  • Older age, as most patients tend to be older than 60 years of age
  • Family history of genetic syndromes which predispose to cancer, such as familial adenomatous polyposis, Lynch syndrome, etc
  • Chronic inflammation of the colon, such as ulcerative colitis

What are the symptoms?

In the early stages of colorectal cancer, there is usually no symptom, or the symptoms are very mild and vague. By the time the more classical symptoms appear, the cancer may already be at an advanced stage.


Some of these “classical” symptoms are:


A change in your bowel habit – either becoming more frequent, or becoming more constipated, or irregular bowel habit

Bleeding in your stools

A sensation of inability to completely empty your bowel

Stools becoming pencil-thin in diameter

Recurrent or persistent abdominal pain or bloating

Unexplained weight loss

Weakness or feeling easily tired

Anaemia (a drop in your haemoglobin level)

What will the doctor do to diagnose the cancer?

The ideal test is to perform a colonoscopy. This allows the doctor to visualize the cancer, accurately locate the part of the colon or rectum where the cancer is, and obtain tissue biopsy to confirm the diagnosis.


Following the diagnosis of the cancer, the doctor may organize scans like CT scan to check if the cancer has spread. For cancer of the rectum, he may also organize a MRI or ultrasound scan of the rectum to decide if radiotherapy & chemotherapy is required.


What is the treatment of colorectal cancer?


Depending on what is the stage of the cancer, the doctor will then decide on the appropriate treatment. The ideal treatment is surgical removal of the cancer, as well as the lymph nodes around the cancer. Currently many of the operations to treat colorectal cancer can be performed by laparoscopic methods (or keyhole surgery).


Other treatment methods for colorectal cancer include chemotherapy and radiation therapy.


The type of surgery depends on the location of the cancer.


If the cancer is in the sigmoid part of the colon or the rectum, the surgery is called Anterior Resection (click to read more about this surgery). This can be done by laparoscopic method (laparoscopic anterior resection) or the traditional open method.


  • The removal of the sigmoid colon and part of / whole of the rectum.
  • The affected part of the sigmoid colon and/or rectum is removed, and the cut edges are joined back if it is possible.
  • Some patients may require a stoma formation after this procedure. The stoma is usually temporary. This depends on several factors, which your surgeon will discuss with you.
  • After surgery, the patient is usually kept fasted overnight, and fluid intake is commenced the following day. The patient is gradually advanced to solid food, depending on the rate of bowel recovery.


If the cancer is in the ascending colon, transverse colon, or descending colon, the surgery is called Colectomy (click to read more about this surgery). This can be done by laparoscopic method (laparoscopic colectomy) or the traditional open method.


  • A colectomy is the removal of part of the large intestine (or colon), or the entire large intestine.
  • Partial removal is known as a right hemicolectomy, a left hemicolectomy, a transverse colectomy or a sigmoid colectomy, depending on the part of the large intestine that is removed.
  • During the surgery, the affected part of the large intestine is removed, and the cut edges are joined back.
  • Some patients may require a stoma formation after this procedure. A stoma allows the faeces to be drained out through a small incision in the abdominal wall into a bag. The stoma is usually temporary.


How to prevent colorectal cancer?

Go for colorectal cancer screening when you reach the age of 50 years old. This is regardless of whether you are male or female. If you have close relatives who have been diagnosed with colorectal cancer, consider screening earlier. Talk to us about this.


Arrange for consultation


There are various methods to screen for colorectal cancer. Talk to us about the pros and cons of each method.


In terms of prevention, if the colonoscopy is chosen as the screening method, it has the additional benefit of preventing colorectal cancer. This is because through a colonoscopy, we can detect polyps and remove these polyps before they can turn into a cancer.


A healthy lifestyle also helps to reduce the risk of getting colorectal cancer:


  • Stop smoking
  • Eat a well-balanced diet, rich in vegetables and fresh fruits
  • Maintain a healthy weight
  • Exercise regularly

Got any questions?

Call us today to enquire