Colorectal cancer is far more common in Malaysia than most people realise — and it remains one of the leading causes of cancer death globally. The encouraging news is that it's also one of the most preventable and treatable cancers, when caught early.
What exactly is colorectal cancer?
Colorectal cancer develops in the colon or rectum, when cells in the lining of the bowel begin growing in an uncontrolled way. It almost always starts as a small growth called a polyp — a clump of cells on the inner lining of the colon or rectum.
Not every polyp turns cancerous. But certain features raise the level of concern: a polyp larger than 1 cm, the presence of more than three polyps, or a finding called dysplasia — abnormal, pre-cancerous cell changes — after a polyp has been removed and examined.
Dysplasia refers to abnormal, pre-cancerous cell changes within the lining of the colon.
What causes it?
There isn't one single cause of colorectal cancer. At its core, cancer develops when something goes wrong in the DNA that controls how a cell behaves — the cell's internal "instructions" get scrambled, and the cell starts growing and dividing without the usual checks in place.
Over time, these abnormal cells can form a tumour, interrupting the function of healthy surrounding tissue. In more advanced cases, cancer cells may break away from the original tumour and spread elsewhere in the body — a process called metastasis.
What raises your risk?
Risk factors don't directly cause colorectal cancer — but they meaningfully increase the chances of developing it. Some you can't change. Others, you can.
Factors You Can't Control
- Age — most cases occur in people over 50, though younger cases are rising
- Gender — men have a notably higher incidence than women
- Race — in Malaysia, incidence is highest among Chinese, followed by Malay and Indian populations
- Family history — risk rises with more affected relatives or early-onset cases in the family
- Inherited syndromes — conditions like Lynch Syndrome and Familial Adenomatous Polyposis
- Chronic inflammatory bowel disease
Factors You Can Influence
- Diet — high intake of processed food and excessive red meat
- Smoking and alcohol — both raise risk meaningfully
- Sedentary lifestyle — low physical activity is an independent risk factor
- Related conditions — high blood pressure, high blood sugar, and high cholesterol are all linked to increased risk
Colorectal Cancer in Malaysia — By the Numbers
| Most common cancer in Malaysian men | 16.9% |
| 2nd most common cancer in Malaysian women | 10.7% |
| Incidence — Chinese population | 19.6 / 100,000 |
| Incidence — Malay population | 12.2 / 100,000 |
| Incidence — Indian population | 11.0 / 100,000 |
Source: Malaysian National Cancer Registry (MNCR), 2012–2016
What symptoms should you watch for?
In its early stages, colorectal cancer often causes no symptoms at all — which is exactly why screening matters so much. By the time symptoms appear, the disease may already be more advanced. Watch for:
- Blood in the stool, or bleeding from the anus
- Persistent abdominal discomfort — bloating or pain
- Changes in bowel habits — new constipation or diarrhoea
- Unexplained weight loss
- A constant feeling that the bowel hasn't fully emptied
- Unusual fatigue
Screening — your best line of defence
Most colorectal cancers develop slowly, over years, from polyps that can be detected and removed long before they ever become cancerous. This makes screening one of the most effective cancer-prevention tools available.
iFOBT (Immunochemical Faecal Occult Blood Test)
A simple, non-invasive stool test recommended for people aged 50–75 without symptoms. It detects hidden blood in the stool — an early warning sign. A positive result is followed up with a colonoscopy.
Colonoscopy
The gold standard. A thin camera examines the entire colon and rectum, and any polyps found can usually be removed during the same procedure — making it both diagnostic and preventive.
CT Colonography
Sometimes called a "virtual colonoscopy." Uses CT imaging to create a 3D view of the bowel without sedation. Bowel preparation is still required, and any polyps found still need a conventional colonoscopy for removal.
CT and MRI Scans
Used mainly for staging once cancer is diagnosed — to check whether it has spread to lymph nodes, the liver, or elsewhere in the body, and to guide treatment planning.
How is it treated?
Treatment depends heavily on where the cancer is located and how advanced it is at diagnosis.
In the earliest stages, where abnormal cells are confined to the lining of the colon, a polyp or small early cancer can sometimes be removed entirely during colonoscopy itself — no surgery needed.
For more established tumours, surgery becomes the primary treatment. The surgeon removes the affected segment of bowel along with nearby lymph nodes, which are checked for cancer spread. Dr Cha performs this using laparoscopic, robotic, and where appropriate, NOSES (Natural Orifice Specimen Extraction Surgery) techniques — minimising incisions and speeding up recovery without compromising the thoroughness of the cancer operation.
In more advanced cases where cancer has spread beyond the colon, treatment is typically combined with chemotherapy and, in some cases, radiotherapy, coordinated through a multidisciplinary care team.
The key takeaway: Colorectal cancer is one of the few cancers that can genuinely be prevented — not just caught early, but stopped before it starts — through routine screening and timely polyp removal. If you're 50 or older, or have a family history, please don't wait for symptoms to appear.
Dr Cha Kar Huei
Consultant Bariatric, Colorectal & Laparoscopic Surgeon, Hospital Picaso