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What is Colorectal Cancer?
Colorectal cancer is cancer of the colon (the main part of the large intestine) and the rectum (the passageway connecting the colon to the anus).
In most people, colorectal cancers develop slowly over several years. Before cancer forms, a growth of tissue or a tumour usually begins as a non-cancerous polyp on the inner lining of the colon or rectum. A polyp is a benign or non-cancerous growth which may develop into cancer over time. Not all polyps change into cancer and this largely depends on the kind of polyp.
Risk Factors
You have a higher chance of developing colorectal cancer if you:
- Are over 50 years of age
- Have a family history of colon or rectum cancer
- Have a previous history of colon polyps
- Have a history of ulcerative colitis (ulcers in the lining of the large intestine) or Crohn’s disease
- Smoke or have a diet high in fats and low in fruits and vegetables
If you think you may be at risk, you should discuss this with your doctor.
Colorectal Cancer Symptoms
In the early stages, people with colorectal cancer may not experience any symptoms.
In the later stages, common symptoms include:
- A change in bowel habits, including diarrhoea or constipation
- Presence of blood in stools
- Persistent abdominal discomfort such as cramps, gas or pain
Related: Signs and Symptoms of Colorectal Cancer
Colorectal Cancer Screening
For average-risk individuals, screening for colorectal cancer should begin at age 50 years. FIT is one of the recommended screening tests and should be performed annually.
Average-risk individuals:
i) are asymptomatic (no symptoms or signs)
ii) do not have a family history of colorectal cancer
iii) have a family history of colorectal cancer among non-first-degree relatives (i.e not parents or siblings) or relatives who got diagnosed older than 60 years old
You can undergo colorectal cancer screening (using FIT) through HPB's Healthier SG Screening. You will be given two FIT kits because two stool samples should be collected over two days for a more accurate result.
Screening with FIT should be done once a year. However, if you develop any colorectal cancer symptoms such as blood in stools, changes in bowel habits etc, please see your doctor immediately even if you had a normal FIT result.
If your doctor assesses your risk level to be increased or high, then he/she might suggest colorectal cancer screening via colonoscopy. Please refer to the table below for the screening frequency.
For individuals at increased risk or high risk, screening by colonoscopy is also indicated. Please refer to the table below
| High-risk groups | Age (years) | Frequency of colonoscopy screening |
Family history of colorectal cancer in
|
10 years prior to the youngest case in the family or at age 40, whichever is earlier | Every 5 years |
| Family history of colorectal cancer in first degree relative age > 60 years | From age 50 | Every 5-10 years |
| Family history of confirmed advanced adenoma(s) or advanced sessile serrated polyps (SSPs)/sessile serrated lesion (SSLs) in first degree relative at any age | From age 40, or at the age the relative was diagnosed, whichever is earlier | Every 5-10 years, if the results continue to be normal |
| Personal history of cancers associated with Lynch syndrome such as ovarian or endometrial cancer | After resection of the uterus and/or ovaries | - |
| Family history of familial adenomatous polyposis (FAP) | From age 10-12e | Annually |
| Family history of hereditary non-polyposis colorectal cancer (as defined by Amsterdam IIf or Bethesda criteriag) and/or Lynch syndrome | From age 20-25 | Every 1-2 years |
|
Personal history of inflammatory bowel disease
(a) Left-sided colitis (b) Pan-colitis |
(a) From 15th year of diagnosis
(b) From 8th year of diagnosis |
Every 1-2 years |
e Flexible sigmoidoscopy from age 10 to 12 years (puberty) until adenomas are identified, upon which screening is switched to colonoscopy.
f Amsterdam II criteria: ≥ 3 relatives with a Lynch syndrome-related cancer (colorectal, endometrial, small bowel, ureter, or renal pelvis) and meet the following additional criteria:
- ≥ 2 successive generations affected.
- One is a first-degree relative of the other two.
- ≥ 1 relative was diagnosed age < 50 years.
- No evidence of FAP.
- Tumours are verified by pathological examination.
g Bethesda criteria:
- Colorectal cancer diagnosed in a patient age < 50 years.
- Presence of synchronous or metachronous, colorectal, or other Lynch syndrome-related tumours, regardless of age.
- Colorectal cancer with microsatellite instability (tumour-infiltrating lymphocytes, Crohn-like lymphocytic reaction, mucinous or signet-ring differentiation, or medullary growth pattern).
- Colorectal cancer diagnosed in a patient with ≥ 1 first-degree relatives with a Lynch syndrome-related cancer, with one of the cancers diagnosed age < 50 years.
- Colorectal cancer is diagnosed in a patient with ≥ 2 first- or second-degree relatives with Lynch syndrome-related cancers regardless of age.
Colonoscopy
Colonoscopy is one of the recommended screening tests for the average risk asymptomatic population, from age 50 years. For screening the general population at average risk, colonoscopy should be performed at an interval of no more than 5 to 10 years.
The screening colonoscopy:
- Uses a flexible tube (colonoscope) to look at the inner lining of the large intestine (colon and rectum)
- Takes about 20 to 30 minutes to complete
- Has to be done in a hospital by a doctor trained in conducting colonoscopies
Discuss with your doctor which screening test is best for you.
For more information about your recommended screening for colorectal cancer, visit the Healthier SG Screening page.
Colorectal Cancer Treatment
The three main treatment options for colorectal cancer are surgery, chemotherapy and radiation. These options may be used alone or in a combination.
- Colorectal surgery: this involves removal of the part of the colon that contains the cancer cells.
- Chemotherapy: chemotherapy can be used to destroy cancer cells after surgery, to control tumour growth or to relieve symptoms of colorectal cancer.
- Radiation therapy: radiation therapy uses X-rays to kill any cancer cells that might remain after surgery, to shrink large tumours before an operation so that they can be removed more easily, or to relieve symptoms of colorectal cancer. Side effects of radiation therapy may include:
- Diarrhoea
- Rectal bleeding
- Fatigue
Lower Your Colorectal Cancer Risk
A healthy lifestyle can help reduce the risk of colorectal cancer and many other medical conditions. Take steps to reduce your risk of colorectal cancer by:
- Eating plenty of fresh fruits, vegetables and whole grains which contain fibre and antioxidants
- Limiting fat intake especially saturated fat from animal sources such as fatty meat, red meat and full cream dairy products
- Limiting alcohol intake
- Quitting smoking
- Staying physically active and maintaining a healthy body weight
Contributed By
- Health Promotion Board
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