Article contributed by Dr Winson Tan, Head & Senior Consultant for Colorectal Service at Sengkang General Hospital (SKH), a member of the SingHealth group.

Colorectal cancer (colon cancer) is the top cancerⁱ affecting men and women in Singapore.

The life time risk of developing colorectal cancer (also known as colon cancer) in Singapore for males is about 4.4%, while for females, it is about 3%ⁱ.

Unfortunately, a majority of colorectal cancers are diagnosed at stages three and four​.​​

Related article: Colorectal Cancer Increasingly Found in Young Adults Under 50

Watch this video on colorectal cancer!

FAQs about colorectal cancer (colon cancer)

1) Is colorectal cancer preventable?

Prevention of colorectal cancer (colon cancer) is definitely possible as a majority (>80%) of cancer cases develop from pre-cancerous colonic polyps.ⁱⁱ

Regular screening is the best way to detect colorectal polyps or cancer early.

Routine screening tests include:

• Faecal Immunochemical Test (FIT) (yearly)
  Blood in the stool may be an early sign of colorectal cancer (colon cancer). FIT is used to detect the presence of human blood in the stool. If blood is found, additional tests can confirm the source of the blood and if it is cancer.

• Colonoscopy (every 5-10 years) 
  During this procedure the colon and rectum are examined using a special flexible camera inserted through the anus. It allows the removal of small polyps and biopsy of any abnormal areas. 

  Removal of these pre-cancerous colonic polyps has been shown in studies to reduce the incidence of colorectal cancer (colon cancer) by up to 80%.ⁱⁱⁱ
  

  Thus, colonoscopy screening, with removal of pre-malignant polyps at the same setting, offers the most effective means of preventing colorectal cancer.

In addition to regular screening, a healthy lifestyle may help to prevent colorectal cancer (colon cancer). This includes:

• Moderation of alcohol consumption,

• Quit smoking (if you haven't) or not starting smoking,

• Regular physical activity (exercise) and a

• Balanced diet that includes adequate fruits, vegetables and whole grains, while limiting the consumption of fat.

Related article: More Tips to Lower Colorectal Cancer Risk

2) Are all (colonic) polyps the same?

There are many different types of colonic polyps. While not all of them may lead to cancer, the majority of colonic polyps discovered carry a risk of malignant transformation (adenomatous polyps).

The risk of cancer developing from adenomatous polyps also varies according to factors such as the:

• Size of the polyp and the

• Extent of abnormality on microscopic examination (degree of differentiation).

3) My relative has colorectal cancer. What is my risk?

In general, having a higher risk of developing colorectal cancer can be attributed to:

• Being over 50 years of age

• Having a family history of colon or rectum cancer

• Having a previous history of colon polyps

• Having a history of ulcerative colitis (ulcers in the lining of the large intestine) or Crohn’s disease

• Smoking or having a diet high in fats and low in fruits and vegetables

When assessing your risk of developing colorectal cancer (colon cancer) based on family history, there are multiple factors that need to be considered:

1. The number of family members who have colorectal cancer (colon cancer),

2. Whether family members who have colorectal cancer are first degree relatives (parents, siblings or child) and

3. The age your relatives were diagnosed with colorectal cancer (colon cancer).

As a crude estimation, those with one first degree relative with colon cancer carry a 2-fold higher risk of developing it, while those with 2 or more relatives carry at 4-​fold higher risk of developing it.^v

4) What are signs that I should look out for?

In the early stages, colorectal cancer may not cause any symptoms. 

In later stages, symptoms may include:

• Persistent diarrhoea or constipation

• Blood in the stools or rectal bleeding

• Change in the consistency or calibre of stools

• General abdominal discomfort (bloating, fullness, cramps or gas)

• A feeling that the bowel does not completely empty after emptying the bowels

• Constant tiredness

• Severe appetite or weight loss

When should I see a doctor?

The symptoms above can be caused by a number of reasons and may not indicate the presence of cancer. However, make an appointment with your doctor if you have any signs or symptoms that worry you.

5) Is chemotherapy needed for colorectal cancer treatment after surgery?

It is important to understand that the main treatment for curable colorectal cancer (colon cancer) is surgery.

Chemotherapy’s role is mainly to augment the surgical treatment so as to reduce the likelihood of cancer recurrence.

Thus, chemotherapy is usually recommended for patients with cancers that are deemed to be at higher risk of recurrence.

These are usually patients with cancers that have involved the lymph nodes (stage III cancer). An oncologist may also recommend chemotherapy in certain patients with stage II cancers that exhibit features which put them at an increased risk of recurrence.

Ref: H24 (ed)

Sources
i. Singapore Cancer Registry Annual Report 2022.
ii. N Engl J Med 2016; 374:1065-1075 Colorectal Adenomas. Williamson B. Strum
iii. N Engl J Med. 1993 Dec 30;329(27):1977-81.​Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup. Winawer SJ1, Zauber AG, Ho MN, O'Brien MJ, Gottlieb LS, Sternberg SS, Waye JD, Schapiro M, Bond JH, Panish JF, et al.
v. Butterworth AS, Higgins JP, Pharoah P. Relative and absolute risk of colorectal cancer for individuals with a family history: a meta-analysis. Eur J Cancer 2006;42:216–27

Check out other articles on colorectal cancer (colon cancer):

7 Effective Ways to Prevent Colorectal Cancer

Colorectal Cancer: Commonly Asked Questions Answered!

Colorectal Cancer Treatment: What Are Your Options?

Suspect You May Have Colon Cancer? Here's What to Do