Understanding Colon Cancer
What Is Colon Cancer?
Colon cancer is a malignant tumour that develops in the large intestine (colon). In the most common type, adenocarcinoma colon cancer, it often begins from a small growth called a polyp. This growth appears on the colon’s inner lining and may eventually become cancerous.
This is one of the most commonly diagnosed cancers in Singapore. With modern treatments, it is now possible to achieve long-term remission.
The Causes and Risk Factors of Colon Cancer
Many cases of colon cancer begin when a non-cancerous growth called an adenomatous polyp first forms on the inner lining of the colon or rectum. Some of these polyps can turn cancerous over time as the cells accumulate DNA mutations, and the cancer may then spread.
The exact cause of these genetic mutations is not yet fully understood. However, there are several risk factors that increase the chance of developing colon cancer:
- Smoking
- Type 2 diabetes
- Being over the age of 50
- Prior radiation exposure
- Obesity and physical inactivity
- A family history of colon cancer
- Heavy alcohol consumption
- Chronic inflammatory bowel disease (IBD)
- A personal history of polyps or colorectal cancer
- Having an unhealthy diet (e.g. one low in fibre and high in fat)
- A family history of hereditary issues like Lynch Syndrome and Familial Adenomatous Polyposis (FAP)
Signs and Symptoms of Colon Cancer
In its early stages, colon cancer may not cause any noticeable symptoms. Polyps and small tumours can grow unnoticed in the colon or rectum for years.
We have provided the common warning signs of the condition below. However, bear in mind that symptoms can vary from person to person. The tumour’s location may also affect a patient’s symptoms.
Here are the symptoms to look out for:
- Changes in bowel habits
- Blood in the stool or rectal bleeding
- Abdominal pain or discomfort
- Change in bowel movement, consistency or form
- Unexplained weight loss and loss of appetite
- Constant fatigue or weakness
- Abdominal bloating or palpable mass
Get Assessed and Diagnosed for Colon Cancer
If you think you may have colon cancer or are experiencing its symptoms, let our specialist assess and diagnose you.
How Colon Cancer Is Diagnosed
Your doctor will usually begin your clinical evaluation with a request for your medical history and ask about the symptoms you’re experiencing. You may also need diagnostic tests to detect polyps or abnormalities in the colon and rectum.
Some key diagnostic tests your doctor may perform are the following:
- Faecal occult blood test (FOBT) or FIT: This non-invasive stool test can detect hidden blood in your faeces. It does not confirm cancer on its own, but it signals that further investigation is needed
- Blood tests: These can check for anaemia, elevated liver enzymes (a sign that cancer has spread to the liver), and a tumour marker called CEA (Carcinoembryonic Antigen) that some colon cancers produce.
- Colonoscopy or sigmoidoscopy: A flexible camera can be inserted through the anus to examine the colon & rectum, and even remove small polyps or take tissue samples for biopsy.
- Imaging scans such as CT and MRI: These are used to see the size and location of the colon tumour and check if the cancer has spread to nearby lymph nodes or distant organs like the liver or lungs.
Potential Complications of Colon Cancer
Colon cancer can cause serious complications if not treated in a timely manner. These complications include:
- Bowel obstruction: A tumour in the large intestine can grow big enough to partially or completely block the intestinal passage. When digested material and gas cannot pass through, it leads to severe abdominal pain, bloating, and even vomiting of stool-like contents.
- Gastrointestinal bleeding and anaemia: There are often fragile blood vessels on the surface of large intestine cancer tumours. Because these are prone to suffering chronic bleeding, they can lead to signs of anaemia like fatigue and shortness of breath.
- Perforation of the colon: A tumour can erode through the full thickness of the colon wall, creating a hole (perforation) that lets intestinal contents leak into the abdominal cavity. It can lead to peritonitis or a severe abdominal infection.
- Cancer spread (metastasis): Colon cancer can spread beyond the colon by entering the bloodstream or lymphatic system. This can cause a variety of problems such as liver dysfunction or jaundice with liver cancer, and breathing problems with lung cancer.
Treatment of Colon Cancer
Treatment for colon cancer depends on the stage of the cancer and the patient’s overall health. It often involves a combination of surgery to physically remove the tumour and non-surgical therapies like chemotherapy to kill any remaining cancer cells.
Non-Surgical Treatments
This category of colon cancer treatments includes chemotherapy. These are often used in addition to surgery, but may also be used on their own if surgery is not feasible.
- Chemotherapy: This uses potent drugs to kill cancer cells. In colon cancer, chemotherapy is commonly given after surgery to wipe out any cancer cells left behind and reduce the risk of recurrence. This is also the main treatment for Stage IV colon cancer that cannot be completely removed surgically.
- Targeted therapy and immunotherapy: These are newer forms of systemic therapy that specifically target cancer cells or help the immune system fight them. They are drugs designed to interfere with specific molecules that tumours use to grow.
For example, some colon cancers overproduce a protein called EGFR or VEGF, and targeted drugs can block those. These therapies are typically used in advanced colon cancer or cases where standard chemo isn’t working. - Radiation therapy: This uses high-energy X-rays or other radiation to kill cancer cells in a specific area. However, it is not routinely used for colon cancer because the colon is mobile in the abdomen.
Early-stage (Stage I) colon cancer might not require any chemotherapy after surgery. However, Stage III (lymph node involvement) typically does. Meanwhile, Stage IV will involve a personalised combination of chemotherapy, targeted therapy, or immunotherapy.
Your colorectal team will personalise your treatment based on your health and cancer type. Genetic testing may provide additional information to guide care, and your team will monitor progress and adjust treatment as needed.
Surgical Treatments
Surgery is the cornerstone of treatment for localised colon cancer. This is cancer that has not yet spread to distant organs.
- Polypectomy & local excision: Small cancers can sometimes be removed during the colonoscopy itself. In a polypectomy, the doctor uses a snare passed through the colonoscope (the tube inserted into the colon) to cut off the cancerous polyp.
For slightly larger early tumours, an advanced endoscopic technique or a local excision surgery can shave off the cancer from the colon wall. - Colectomy (colon resection surgery): This removes the section of the colon that contains the tumour, along with a margin of normal colon on either side and the associated lymph nodes in that segment.
After cutting out that segment, the surgeon may either join the two ends of the colon back together in a process called anastomosis or create a stoma via colostomy, depending on the circumstances. - Metastasis surgeries: In cases where colon cancer has spread, but only to one or two spots, surgery can sometimes be used to remove metastases or secondary tumours that have come from the cancer’s spread.
This can occasionally lead to long-term remission in select Stage IV patients. These procedures are considered on a case-by-case basis and often done in combination with chemo.
Your doctor will discuss the expected recovery time after a surgery (typically several weeks) and whether you need any additional treatments like chemotherapy. They typically perform a lab analysis of the removed section to get a pathology report that will confirm the type of cancer, whether it has been completely excised, and how many lymph nodes were involved.
Recovery and Prognosis for Colon Cancer
The recovery varies based on the treatment approach taken:
- Surgery patients spend about 1 to 2 weeks in the hospital and several weeks at home regaining strength. If you have a temporary stoma, you will learn stoma care before going home.
- Chemotherapy side effects usually resolve a few weeks after the last dose. If you require chemotherapy after surgery, your recovery will involve going through the chemo cycles. Chemotherapy for colon cancer is typically given over a span of 3 to 6 months, so you might receive it as an outpatient every few weeks.
The prognosis for colon cancer is usually discussed in terms of 5-year survival rates, which vary greatly by stage:
- Stage I colon cancer (tumour is limited to the inner layers of the colon) has a 5-year survival rate of 80-90%.
- Stage II colon cancer (tumour is through the colon wall but not in the lymph nodes) often has a cure rate in the 70-90% range, depending on specific features.
- Stage III (cancer has spread to nearby lymph nodes) is a more advanced situation, but with surgery and chemotherapy, 5-year survival rates range around 50–80%, depending on how many nodes are involved.
- Stage IV (metastatic colon cancer) historically has a prognosis with 5-year survival rates under 15%.
Note that even when Stage IV colon cancer isn’t curable, modern chemotherapy and targeted therapies can extend life significantly. Many patients live multiple years with metastatic disease now.
Consistent treatment and regular follow-ups are important. This may include routine check-ins with your colorectal specialist, periodic blood and stool tests, and other forms of colon cancer screening.
Prevention and Management Tips
Early detection and healthy lifestyle habits can lower your risk of colon cancer. Below are some tips that may help you manage it.
- Get regular screening: Screenings like colonoscopies can help to detect colon cancer early. In Singapore, average-risk individuals are currently advised to start screening at age 50.
Learn more about colorectal screenings → - Eat a high-fibre, balanced diet: Aim to eat plenty of vegetables, fruits, and whole grains, which provide fiber and nutrients that support colon health. Try to limit red meat and processed meats (e.g. bacon, ham, sausages), and high-fat foods. These have been linked to higher colon cancer risk.
- Maintain a healthy weight and stay active: Regular exercise and keeping a healthy body weight can reduce your risk of colon cancer. People who are obese have a higher risk of colon cancer.
- Avoid smoking: Long-term smoking is associated with many cancers, including colon cancer. The carcinogens in tobacco can circulate throughout your body and damage DNA in colon cells too.
- Limit alcohol consumption: Drink in moderation, if at all.
- Manage medical risk factors: If you have conditions like inflammatory bowel disease or diabetes, work with your doctor to manage them well.
- Stay vigilant and follow up: Even after a clean screening test, remain watchful for any new symptoms and report them. If you have already had colon cancer and been treated, adhere to your follow-up schedule of colonoscopies, scans, or clinic visits. This ensures that any sign of recurrence is caught early.
Conditions
Schedule an Appointment for Colon Cancer Screening
If you have symptoms or concerns about colon cancer, book a consultation with our specialist for an assessment. We can provide an early evaluation and propose a treatment plan if needed.