Colorectal cancer is an umbrella term for cancers that develop in the colon or rectum. Although both organs form part of the large intestine, their location and surrounding anatomy differ, which may influence symptoms and treatment planning.
Colon cancer may cause changes in bowel habits, abdominal discomfort, bleeding or anaemia, depending on where the tumour develops. Rectal cancer is located closer to the anus and may be more likely to cause rectal bleeding, bowel urgency or a persistent feeling that the bowel has not emptied fully.
Age is the single most important risk factor for colorectal cancer, with the risk increasing substantially after the age of 50. Although younger people can also develop colorectal cancer, approximately 75–80% of patients diagnosed are over the age of 55.
Individuals with a family history of colorectal cancer are at increased risk, particularly if multiple family members are affected, those affected are first-degree relatives or one or more were younger than 50 when diagnosed.
However, more than 80% of patients have sporadic colorectal cancer. This means that most people diagnosed with colorectal cancer do not have a family history of the disease.
The risk of colorectal cancer may be higher among people who:
Early stage colorectal cancer usually does not manifest any symptoms. Hence by the time there are symptoms, it is likely that intermediate or late stage cancer may be diagnosed.
Some symptoms of colorectal cancer include:
Regardless of age, having these symptoms does not mean that you definitely have colorectal cancer. Rather, it means that you should consult a colorectal surgeon, so that tests can be performed to assess if you have cancer.
Yes! Colorectal cancer almost always develops from precancerous polyps. Hence regular screening with colonoscopy is the key to preventing colorectal cancer.
In Singapore, screening for individuals at average risk of colorectal cancer is recommended from the age of 50. Those with a family history of colorectal cancer may need to begin earlier.
For example, if one first-degree relative was diagnosed at age 60 or younger, or if two or more first-degree relatives have had colorectal cancer, screening may begin at age 40 or 10 years before the youngest relative was diagnosed, whichever comes first. Individuals who are uncertain about when to start should discuss their personal and family history with a doctor.
You may also want to book an assessment if you:
These signs do not necessarily indicate colorectal cancer, but further assessment may be needed to determine their cause.
Colorectal cancer screening can detect signs of cancer or precancerous polyps before symptoms develop. However, an abnormal screening result does not confirm a diagnosis. A colonoscopy is usually required to examine the colon and rectum, while a tissue sample may be taken for testing if a suspicious growth is found.
A yearly faecal occult blood test is a common population screening method. It detects small amounts of blood in the stool that may not be visible.
The test can help identify signs of colorectal cancer but is not designed to detect most polyps, as smaller polyps do not usually bleed. Individuals with a positive result will require a colonoscopy to determine the cause of the bleeding and check for colorectal cancer.
During a colonoscopy, the doctor examines the inner lining of the colon and rectum using a thin, flexible tube with a camera. This method can detect and remove precancerous polyps before they develop into cancer.
If cancer has already developed, screening colonoscopy may detect it at an earlier stage, when treatment is more likely to be curative. A tissue sample can also be collected during the procedure to confirm the diagnosis.
Faecal occult blood testing and colonoscopy are the main colorectal cancer screening methods recommended in Singapore. If these methods are unsuitable, alternative imaging-based tests may sometimes be considered. However, these tests cannot remove polyps or collect tissue samples, so any abnormal findings will still need to be examined through a colonoscopy.
CT colonography uses computed tomography imaging to produce detailed images of the colon and rectum. It may detect polyps or other abnormalities but does not allow tissue samples to be taken or polyps to be removed during the examination.
A double-contrast barium enema uses X-rays and contrast material to examine the colon. It is less commonly used for colorectal cancer screening than a faecal occult blood test or colonoscopy.
Colorectal cancer is often treatable and may be cured, particularly when it is detected at an early stage. Treatment depends on whether the cancer begins in the colon or rectum, its stage, whether it has spread and the patient’s overall health.
Early-stage colorectal cancer is commonly treated with surgery. Some patients with Stage II or Stage III disease may also require systemic therapy, while radiotherapy may form part of the treatment plan for rectal cancer.
For Stage IV colorectal cancer, systemic therapy is more commonly used, although surgery may still be considered in selected cases.
Colorectal cancer surgery generally involves removing the tumour together with the affected section of the colon or rectum and nearby lymph nodes. It is commonly recommended when the cancer can be removed completely and may also form part of treatment for selected locally advanced or metastatic cancers.
After the affected section is removed, the surgeon may reconnect the healthy ends of the bowel so that bowel function can continue without a stoma. In some cases, a temporary stoma may be created to allow the bowel to heal. A permanent stoma may be required when the remaining bowel cannot be safely reconnected or when a low rectal tumour affects the anal sphincter.
Many patients may also be suitable for minimally invasive colorectal cancer surgery, performed either laparoscopically or robotically using the da Vinci surgical system. The recommended approach depends on the tumour’s location and complexity, previous abdominal surgery and the patient’s overall condition.
Surgery may be the main treatment or one part of a broader treatment plan. For colon cancer, chemotherapy may be recommended after surgery to reduce the risk of recurrence. For rectal cancer, systemic therapy, radiotherapy or both may be given before surgery.
For advanced colorectal cancer, systemic therapy may be the main treatment, with surgery considered in selected cases. Depending on the cancer’s molecular features, systemic treatment may include chemotherapy, targeted therapy or immunotherapy.
When surgery is recommended, it may be performed using an open, laparoscopic, robotic or transanal approach.
This is the traditional surgical approach. The colorectal cancer surgeon makes a larger incision in the abdomen to access the bowel and remove the tumour together with the affected section of the colon or rectum.
This is a minimally invasive procedure in which several small incisions are made. A thin tube with a camera and light, known as a laparoscope, is inserted together with long, slender instruments. These allow the surgeon to visualise and remove the affected section of the bowel.
In this technique, specialised surgical instruments are inserted through small incisions and attached to robotic arms. The surgeon controls these instruments from a console to perform the procedure with precise movements.
Benign rectal polyps and selected early-stage rectal cancers may be removed through the anus using specialised instruments. This may avoid the need to remove an entire section of the bowel in suitable patients.
Potential advantages of minimally invasive surgery may include:
These advantages vary between patients. Open surgery may still be the safer or more suitable approach for some cancers.
Dr Tan Wah Siew, our senior consultant colorectal surgeon, has extensive experience in laparoscopic and robotic colorectal surgery. Through minimally invasive surgery, she aims to carry out treatment with less postoperative pain and a shorter recovery period.
Before undergoing colorectal cancer surgery, you may need to make certain preparations. These may include:
After surgery, you will be taken to a recovery area where your vital signs will be monitored. You may experience some pain and discomfort, but medication will be provided to manage it. Antibiotics may also be given when clinically required.
If a bowel resection is performed, you may need to remain in hospital for approximately 4–7 days. The length of your stay will depend on the type of surgery performed, your recovery and whether any complications develop.
Once your doctor determines that it is safe for you to return home, you will be discharged with instructions on wound care, diet, physical activity and follow-up appointments. Following these instructions can support a smoother recovery.
After colorectal cancer surgery, proper wound care and appropriate dietary and lifestyle changes are important. This includes drinking plenty of fluids, following the recommended diet and gradually resuming physical activity as advised by your physiotherapist or surgical team.
You should also watch for signs of infection or other complications, such as worsening abdominal pain, bleeding or fever. Contact your colorectal cancer doctor promptly if you develop these symptoms or seek urgent medical attention if they are severe.
Timely assessment can help identify colorectal cancer at an earlier stage and determine the treatment that may be required. Whether you have concerning symptoms, an abnormal screening result or a confirmed diagnosis, specialist guidance can help you understand what to do next.
At Surgical Associates, Senior Consultant Colorectal Surgeon Dr Tan Wah Siew can assess your concerns, review your test results and discuss the appropriate next steps. If surgery is required, she can explain the available approaches and how the procedure may fit into your wider treatment plan.
Schedule a consultation with Dr Tan Wah Siew for an assessment and personalised guidance on colorectal cancer treatment.
Colorectal cancer may be cured, particularly when it is detected early and can be completely removed. The likelihood of successful treatment depends on factors such as the cancer’s stage, location and response to treatment. Localised colon cancer is considered highly treatable and often curable.
Yes. Colorectal cancer may not cause noticeable symptoms during its early stages. Many colorectal cancers develop from precancerous polyps over several years, which is why regular screening is important even when you feel well.
Eating a diet high in fiber, such as fresh fruits and vegetables, whole grains, beans and legumes, can help reduce your risk for colorectal cancer. Additionally, avoiding processed foods and limiting red meat intake can also help lower your risk. A higher Vitamin D intake has also been found to reduce the risk of colorectal cancer.
Haemorrhoids and colorectal cancer can both cause rectal bleeding, so it may not be possible to distinguish between them based on this symptom alone. Colorectal cancer may also cause persistent changes in bowel habits, unexplained weight loss, abdominal discomfort or anaemia.
The average life-time risk of contracting colorectal cancer is about 5% in Singapore. This risk increases by 3 to 5 times if you have a first-degree relative (e.g. a parent) who has had colorectal cancer. The risk is also further increased if the relative developed colorectal cancer at a young age (< 50 years old).
Colorectal cancer usually takes several years to develop from a benign polyp to cancer – all while potentially not displaying any symptoms through the early stages of cancer. The risk of developing cancer and polyps increases with age. This makes timely colonoscopies all the more important,as precancerous polyps can be removed before they have a chance of progressing to cancer.
Yes. The liver is one of the organs to which colorectal cancer may spread. Treatment may involve systemic therapy, surgery or tumour ablation depending on the number and location of the liver tumours, whether cancer is present elsewhere and the patient’s overall health. Surgery may still offer the possibility of long-term disease control or cure in selected patients with resectable liver metastases.
Not everyone requires a stoma after colorectal cancer surgery. Whether one is needed depends on the tumour’s location, the amount of bowel removed and whether the remaining sections can be safely reconnected.
A temporary stoma may be created to allow the bowel to heal after surgery. A permanent stoma may be required if the cancer involves the lower rectum or anal sphincter and these structures cannot be preserved. Your colorectal cancer surgeon will discuss this possibility with you before the procedure.
Senior Consultant Colorectal Surgeon
MBBS, MMed (Surgery), FAMS, FRCSEd
Dr Tan Wah Siew is a senior consultant colorectal surgeon at Surgical Associates with
experience in colorectal cancer and complex bowel conditions. Her approach emphasises
personalised surgical planning and compassionate care throughout the treatment journey.
Before entering private practice, she served in the Department of Colorectal Surgery at
Singapore General Hospital, where she became the hospital’s first female consultant
colorectal surgeon.
Dr Tan further advanced her expertise through a Ministry of Health-sponsored fellowship
at St James’s University Hospital in the United Kingdom, receiving specialised training
in minimally invasive and robotic colorectal surgery, inflammatory bowel disease surgery
and advanced and recurrent pelvic cancers.
Mount Elizabeth Medical Centre
#08-07, 3 Mount Elizabeth, Singapore 228510
Tel: 6454 0054
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Fax: 6764 0054
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Email: ask@surgicalassociates.sg
Gleneagles Medical Centre
#05-01, 6 Napier Road, Singapore 258499
Tel: 6471 0054
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Fax: 6271 0054
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