All About Colorectal Cancer (Colon Cancer) by NCCS

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About this ‘Ask the Specialist’ Q&A:

All About Colorectal Cancer

Colorectal cancer (also known as colon cancer) is a type of cancer that starts in the colon or rectum.

Nearly all colorectal cancers begin as polyps, which are benign growths on the inner lining of the colon or rectum.

Colorectal cancer is the second most common cancer in Singapore, affecting approximately 45 out of every 100,000 people here.

For men, it is the second most common type of cancer and for women, it comes second after breast cancer.

During a period of five years, between 2019-2023, 12,950 cases of colorectal cancer were diagnosed in Singapore.

Have questions about colorectal cancer (colon cancer)? Don’t miss this opportunity to get them answered by our specialist from National Cancer Centre Singapore (NCCS). This Q&A is for a limited time only!

About Asst Prof Dawn Chong

Assistant Professor Dawn Chong is a Senior Consultant Medical Oncologist at the Division of Medical Oncology, National Cancer Centre Singapore (NCCS), and specialises in gastrointestinal cancers.

She is the lead for cancer screening and prevention at NCCS and the co-lead for Impact and Population Health (Platform 5) of the Singapore Translational Cancer Consortium under Consortium for Clinical Research and Innovation Singapore, Ministry of Health.

Her research interests include cancer epidemiology, leveraging on epidemiological and clinical datasets to inform population health approaches and policy, and novel cancer screening methodologies.

Asst Prof Chong works on initiatives with the aim of improving cancer screening rates, cancer detection and public health outcomes.

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Hi Asst Prof Dawn Chong, thank you for this Q&A opportunity to answer questions about colon cancer.

Recently, as I just turned 51, I had enrolled with Healthier SG and did a fecal test. I was shocked to find out that there was blood in my stool sample. I was then scheduled to go for a colonoscopy after, and fortunately the results came out clear :relieved_face: Here are my questions:

a) What is the recommended frequency to go for a fecal test and colonoscopy, after the age of 50?

b) What are the possible reasons for my stool to have traces of blood during my fecal test?

c) Lastly, am I considered at high-risk of colon cancer if I have an uncle who had it? My parents don’t have it but they did have piles. On that note (sorry if this question is out of topic), is piles hereditary and when should it be removed?

Thank you so much for taking the time to answer my questions!

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I always have blood in my poo for years . What should I do? I am 58 years old

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Thanks in advance if my question is answered. I am just in my 30s but in my 20s there were polyps found and removed during colonoscopy(for some investigation) I was told I needed to do colonoscopy every few years to check but I actually am quite hesitant and don’t really know do I just arrange for one if I don’t have any current symptoms? Or is a stool test like for health screening sufficient?

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I am in my mid-forties and over the past few weeks, i have notice that at bedtime i often feel a strong urge to pass stool, but when i go toilet there is nothing. I do have a normal bowel movement every morning and my stools are generally regular.

During a recent health check-up, i had a routine stool test, which did not show any abnormalities.

Given my age and these new night-time symptoms, what initial checks or investigation would you recommend? Should i consider further tests such as colonoscopy?

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Is there any known connection between colon cancer and breast cancer?

My mother was diagnosed with stage 3 colon cancer two years ago. She had surgery followed by four cycles of XELOX chemotherapy. In June this year, she was also diagnosed with breast cancer that is ER-positive and HER2 3+.

Is it common for someone who has had colon cancer to later develop breast cancer, or could this suggest an inherited cancer syndrome or genetic mutation? Does my mother’s history mean that her children have a higher risk of developing colon cancer, breast cancer, or other cancers? Should she or her children consider genetic counselling and genetic testing?

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I had my annual faecal test early this year and one sample was positive. However, I am a bit skeptical about the result, as I also had piles during the sample taking. The doctor recommended that I go for a colonoscopy, but as I am 76 years old, I am hesitant about it, so I opt to wait for the next annual faecal test result and decide. Is this OK?

Thank You

Jack

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Hi Prof Chong. My last colorectal screening was due in June 2013. My last stool exam was in November 2023 with a negative result. I’m a 74-year-old male. Should i go for a colonscopy? Thank you.

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I’m 64. My last endoscopy was in Jun 2014. My stool test in April 2026 was negative. Shall I go for Endoscopy? Thanks.

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Hi, Dr. How often should I for colonscopy. I am in my 50s with colorectal cancer history in the family. Are the femeles in her 50s in the fanily also advised to do the testing in the same frequency? Thank you.

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Answer by Asst Prof Dawn Chong

Hi Alvin_C,

a) For average risk individual e.g. general population, FIT (Faecal immunochemical test) is recommended every year and Colonoscopy is recommended every 5-10 years.

b) If the colonoscopy shows no cancer, some possible causes include hemorrhoids/piles (swollen veins in rectum or anus), anal fissure (tears in the lining of the anal canal), polyp (benign growth on the lining of the large intestine and rectum), diverticular disease (pouches in the wall of the large intestine), gastroenteritis (infection of intestine), inflammatory bowel disease (inflammation of intestine) which is less common locally.

c) Unfortunately, I am unable to assess whether you are at high risk of colon cancer without detailed information regarding family history of cancer. Piles is not hereditary. Do consult a doctor to assess if there is a need to remove the pile. The need for removal will be dependent on the severity of symptoms e.g. pain, bleeding, the level of prolapse (protrusion of pile that cannot be pushed back easily), ongoing severe symptoms of pain or bleeding despite conservative treatment e.g. medications or presence of blood clot (thrombosis).

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Answer by Asst Prof Dawn Chong

Hi Maryyap,

I recommend that you do a colonoscopy for further evaluation if you have not done one recently. A colonoscopy allows the doctor to inspect the rectum and large intestine (colon) to find out what is the cause of the blood in the stools.

If the doctor finds a benign growth on the lining of the large intestine or rectum (polyp), the doctor often can remove it during the same procedure or take a sample of tissue (biopsy) if something looks unusual.

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Answer by Asst Prof Dawn Chong

Hi Nal,

Usually, a repeat colonoscopy is required after polyps are removed to check for completeness of removal and detect newly formed polyps.

Certain types of polyp e.g. adenoma has a risk of developing into colorectal cancer if left alone and hence removal of these polyps are essential to prevent colorectal cancer.

Depending on the number, type and size of polyps, family history of colorectal cancer or any genetic predisposition (a condition that predisposes an individual to a higher risk of developing colorectal cancer), your doctor will advise on the frequency of colonoscopy.

A stool test will not be sufficient if you have not had a repeat colonoscopy after the initial colonoscopy as advised by your doctor.

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Answer by Asst Prof Dawn Chong

Hi PPC,

Is there any stomach pain or cramping? Do you have a family history of colorectal cancer or genetic predisposition (a condition that predisposes an individual to a higher risk of developing colorectal cancer)?

Given that you have a strong urge to pass stool but there is nothing (tenesmus) for a few weeks, I recommend that you see a doctor for further assessment. The doctor will perform a digital rectal examination (a gloved finger is gently inserted into the rectum to feel for any abnormalities).

There may also be a need for colonoscopy to investigate the cause depending on the assessment.

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Answer by Asst Prof Dawn Chong

Hi Usha,

An individual can have two different types of cancers (e.g. colon and breast cancer) although it is not common.

Given that your mother has breast and colon cancer, I recommend that she sees a genetic counsellor who will review her family history of cancer (which relatives have cancer, what type of cancer, what age were they diagnosed, whether anyone in the family had genetic testing) to determine the need for a genetic test to assess for hereditary cancer syndrome.

Generally, the risk of developing colon or breast cancer increases when a first degree relative (e.g. mother) has breast or colon cancer.

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Answer by Asst Prof Dawn Chong

Dear Jack,

I recommend that you do a colonoscopy for further evaluation if you are suitable for it. The fecal test only indicates whether there is blood in the stool, but it cannot ascertain what is the cause of it.

A colonoscopy allows the doctor to inspect the rectum and large intestine (colon) to find out what is the cause of the blood in the stools. If the doctor finds a benign growth on the lining of the large intestine or rectum (polyp), the doctor often can remove it during the same procedure or take a sample of tissue (biopsy) if something looks unusual.

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Answer by Asst Prof Dawn Chong

Hi Alfred,

Both stool test (FIT) and colonoscopy are recommended ways to screen for colorectal cancer.

If you do not have risk factors e.g. benign growth on the lining of the large intestine or rectum (polyp), family history of colorectal cancer or genetic predisposition (condition that predisposes an individual to a higher risk of colorectal cancer), you do not need to undergo colonoscopy since your FIT is negative in April 2026.

For average risk individual e.g. general population, FIT is recommended every year, and colonoscopy is recommended every 5-10 years.

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Answer by Asst Prof Dawn Chong

Hi Jerry,

I am unable to assess your risk of colorectal cancer without detailed information regarding family history of colorectal cancer including which relatives have cancer, what type of cancer, what age they were diagnosed, whether anyone in the family had genetic testing and presence of genetic predisposition (condition that predisposes an individual to a higher risk of colorectal cancer).

In general, colorectal cancer screening either by FIT or colonoscopy is recommended in individuals aged 50 years and above. For average risk individual e.g. general population, FIT is recommended every year, and colonoscopy is recommended every 5-10 years. The frequency is the same for females.

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