Q. What is colorectal cancer?
A. Cancer is characterised by the development of abnormal cells that destroy normal body tissue, and colorectal cancer is cancer of the bowel. "Colorectal" refers to the colon and rectum, which together make up the large intestine. Colorectal cancer can begin anywhere in the large intestine.
Q. Who is at risk of developing colorectal cancer?
A. Colorectal cancer occurs in both men and women. It is most common among people aged 50 and above. A family history of colorectal cancer or colorectal polyps may increase a person's risk of developing colorectal cancer.
Q. What are the signs and symptoms of colorectal cancer?
A. Early colorectal cancer usually has no symptoms. Signs and symptoms typically occur only when the cancer is more advanced. The absence of symptoms should never be a reason to delay or ignore colorectal cancer testing. Please consult your doctor if you have any abnormal bowel activities.
Q. Is there anything I can do to reduce my risk for colorectal cancer?
A. There is strong scientific evidence that having regular screenings for colorectal cancer beginning at age 50 reduces deaths from colorectal cancer. Screening tests can find precancerous polyps (abnormal growths) in the colon and rectum, and polyps can be removed before they turn into cancer. Studies have also shown that a healthy lifestyle can decrease the risk for colorectal cancer. You can make small steps everyday by increasing physical activity, eating smarter and maintaining a healthy weight.
Q. What are the screening tests for colorectal cancer?
A. Several tests are available to screen for colorectal cancer, talk with your doctor for more details. Doctors recommend regular screening for all adults aged 50 years or above. It is recommended to do fecal occult blood test (FOBT) every year, flexible sigmoidoscopy every 5 years, double-contrast barium enema every 5 years or colonoscopy every 10 years. Persons at higher risk should begin screening at a younger age and may need to be tested more frequently.
Q. Why should I get screened for colorectal cancer?
A. Early detection saves lives. Colorectal cancers almost always develop from precancerous polyps (abnormal growths) in the colon or rectum. Screening tests can find polyps, so that they can be removed before they turn into cancer. Screening tests can also detect colorectal cancer early, when treatment works best and the chance for a full recovery is very high.
QG Is colorectal cancer preventable?
AG Colorectal cancer is a preventable cancer.
QG Who should undergo a routine colonoscopy and why?
AG Colorectal cancer develops in stages. It starts when a colon cell becomes neoplastic and proliferates to form a polyp. Left untreated, the neoplastic polyp will grow and eventually evolve into an invasive cancer. The whole process takes about 10 to 15 years, which gives us a chance to prevent it from occurring. A colonoscopy examination is one of the most effective ways to prevent colorectal cancer, and allows the doctor to examine the whole colonic wall and detect the presence of polyp(s). The doctor can then remove the polyp(s) so that it will not have a chance to grow and turn into cancer. It is recommended to have a colonoscopy examination after 50 years of age, every 10 years. Those with an increased risk of colorectal cancer should start to have colonoscopies at an earlier age and, more frequently. A risk assessment and consultation with a doctor is recommended. Those with hereditary colon cancer syndromes should also consult the Hereditary Gastrointestinal Cancer Genetic Diagnosis Laboratory.
QG If people do not exhibit any unusual symptoms concerning their bowel health, should they still undergo a routine colonoscopy?
AG Yes, because people with polyps will generally not have symptoms. When symptoms occur it is usually too late as the polyp has already evolved into cancer. This explains why in Hong Kong, about half of the people with colorectal cancer were at stage III and IV by the time they visited a doctor.
QG What is involved in undergoing a colonoscopy? How is it performed?
AG Before undergoing a colonoscopy, the bowel needs to be cleaned or prepared. The goal of bowel prep is to eliminate all faecal matter from the colon so that the doctor conducting the colonoscopy will have a clear view. The doctor will provide a solution or tablets to induce bowel motions before the colonoscopy. It is important that one follows the instructions given. Without proper bowel preparation, the colonoscopy will not be successful and may need to be repeated. During a colonoscopy, a doctor will insert a colonoscope (a long tube-like flexible instrument about 130cm in length and 1.5cm in diameter) into the anus and advance it through the rectum and large intestine. The lining of the whole colon and rectum will be examined. If necessary, during a colonoscopy small amounts of tissue can be removed (a biopsy) for analysis and polyps can be identified and entirely removed.
QG Do I have to be admitted to hospital for this procedure? How long How long will I spend in hospital for this procedure?
AG Nowadays, a colonoscopy can be performed as an outpatient procedure and usually takes half a day.
QG If polyps are found during the colonoscopy, are they then removed? How are they removed?
AG Polyps are removed if found during a colonoscopy. This is called polypectomy through a colonoscope. Small polyps can be removed with an instrument that is inserted through the colonoscope to remove the small polyps. Larger polyps are removed by placing a snare around the polyp base and burning through it with electric cautery. The cautery also helps to stop bleeding after the polyp is removed.
QG Are people anaesthetised (put to sleep) during a colonoscopy?
AG A mild sedative medication is usually given before the colonoscopy to prevent pain caused by stretching of the colon.
QG What are the risks associated with undergoing a colonoscopy?
AG The most common complications are bleeding and perforation of the colon. Fortunately, this occurs rather infrequently (one in 1,000 people who have a colonoscopy).
QG Where can I go for a colonoscopy? Do I need a referral from my doctor?
AG All private hospitals and some clinics with specialists in gastroenterology or colorectal surgery can offer a colonoscopy screening. You do not need a referral for a colonoscopy in the private sector. Public hospitals do not provide colonoscopy screening examinations for those without specific symptoms.
QG If polyps are found during a colonoscopy, when should one return to repeat the procedure? If no polyps are found, when should the next routine colonoscopy be scheduled?
AG The interval for the next colonoscopy depends on the assessment of the number, size and histology of the polyp(s) removed, and whether they were completely removed. Individuals should consult with their doctor. The interval for a repeat colonoscopy ranges from two months to five years. If no polyps are found, the recommendation is to have another screening in 10 years time.
QG Many people have heard about the FOBT, how accurate is this in screening for colorectal cancer? Why is it used?
AG The sensitivity of FOBT ranges from 55% to 90%, and its specificity ranges from 70% to 80% in different studies. It is a non-invasive procedure for screening colorectal cancer, under the assumption that colorectal tumours will bleed easily.
QG People with a family history of colorectal cancer should be much more vigilant in undergoing regular screenings as they may be at a greater risk of developing colorectal cancer during their lifetime. For people who have a family history of colorectal cancer, what do you suggest for them to safeguard their health?
No. of first degree relatives (FDR) with colon cancer Risk Recommended colonoscopy screening frequency
One FDR age >50 yrs 2 fold Age 50 onward once every 10 yrs
Two FDR age>50 yrs 3-4 fold Colonoscopy every 5 years, starting at age 40 or 5 years younger than the time of diagnosis in the family
QG What risks are associated with being classified in this group?
No. of first degree relatives (FDR) with colon cancer Risk Recommended colonoscopy screening frequency
One FDR age <50 yrs 4-5 fold Colonoscopy every 5 years, starting at age 40 or 5 years younger than the time of diagnosis in the family
Two FDR, one age<50 yrs 8 fold Colonoscopy every 3-5 years, starting at age 40 or 5 years younger than the time of diagnosis in the family
Three FDR, one age<50 yrs 25 fold Colonoscopy every 2 years, starting at age 20-25, then yearly after age 40

High-risk individuals and families are recommended to consult our Hereditary Gastrointestinal Cancer Genetics Diagnosis Laboratory for genetic tests to determine whether they are affected by one of the hereditary colorectal cancer syndromes. This will alter their risk assessment and the nature and frequency of subsequent screening protocol.
* Thanks to Dr. Siu Tsan Yuen, Deputy Medical Superintendent and Staff Consultant Pathologist of St Paul's Hospital for providing the information above
Myth: Colorectal cancer is a man's disease.
Fact: Wrong. Colorectal cancer is common in women as men. In 2014, 4,979 people were diagnosed with colorectal cancer, 2,117 of which were women.
Myth: Colorectal cancer cannot be prevented.
Fact: Not true. In many cases colorectal cancer can be prevented. Colorectal cancer almost always starts with a small growth called a polyp. If the polyps are found early, doctors can remove them and stop colorectal cancer before it starts.
Myth: It's better not to get tested for colorectal cancer because it's deadly anyway.
Fact: No. Colorectal cancer is often highly treatable. If colorectal cancer is found early and treated, it can significantly improve the chances of a successful recovery.
Myth: Colorectal cancer affects only older people.
Fact: The median age at which colorectal cancer occurs is 70 years, but the risk of developing colorectal cancer starts to rise at age 50. In addition, many young people increase their risk of developing colorectal cancer as a result of poor diet and health. More young people are being diagnosed with colorectal cancer. Among those aged 40-50, the number of new cases has tripled in the past 20 years.
Myth: All types of polyps found in the colon cause cancer.
Fact: False. Adenomatous polyps account for up to 50% of all polyps found in the colon. If they are not removed, they can develop into cancer.
Myth: Colorectal cancer always causes symptoms that are easily recognised.
Fact: Not true. Colorectal cancer may initially have no symptoms at all, or only vague symptoms that are often ignored. A delayed diagnosis can affect chances for successful treatment.
Test your colorectal cancer IQ now! Some questions may have more than one correct answer.


1. Lung cancer is the leading cause of death from cancer. Where does colorectal cancer rank?
  A. 2nd
B. 5th
C. 8th
2. Who is considered most at risk of the disease?
  A. Men age 50+
B. Women age 50+
C. Both men and women age 50+
3. What causes colorectal cancer?
  A. Genetics
B. Diet and environmental factors
C. Stress
4. How can colorectal cancer be prevented?
  A. Lifestyle modifications
B. Regular screening
C. Both A & B
5. What steps should people take if they are at risk of colorectal cancer?
  A. Consult your doctor
B. Go for regular screenings
C. Call the CancerLink FREE service hotline: 3656 0800