Colorectal Cancer - Symptoms, Diagnosis and Treatment Options

What is Colorectal Cancer?

Colorectal cancer, also called colon cancer or bowel cancer, starts in the large intestine (colon) or the rectum, which is the final part of the colon. Colon cancer affects both women and men.

Most colorectal cancers begin as a small growth called a polyp, which can develop in the colon or rectum. Not every polyp becomes cancer, but a polyp that is not found and removed can slowly turn into cancer over time.

Diagram: a simple anatomy illustration of the colon and rectum to go here.

colon cancer anatomy diagram

Colorectal Cancer in Malaysia

According to the Malaysia National Cancer Registry Report 2017 to 2021, colorectal cancer is the most common cancer among men in Malaysia, and the second most common among women after breast cancer.

According to the Malaysia National Cancer Registry Report (MNCR) 2012 to 2016, more than 70% of colorectal cancers were detected at stage III or IV. Knowing the signs and getting screened on time gives you a better chance of finding the disease earlier.

Colorectal Cancer Symptoms

Colorectal cancer may cause few or no symptoms in its early stages, and the signs can be subtle. These are the signs to look out for:

Abdominal pain and tenderness
Blood in the stool
Diarrhoea
Narrow stools
A change in your usual bowel habits
A feeling that your bowel has not emptied fully
Weight loss for no clear reason
Tiredness or weakness

Slow bleeding in the digestive tract can lead to a low red blood cell count, so sometimes the first clue is a routine blood test rather than a symptom you can feel.

Colorectal Cancer Risk Factors

The exact cause of colorectal cancer is not fully known, but several factors can raise your risk. Some cannot be changed, such as age and family history, while others are linked to lifestyle.

Age: the risk increases as you get older, which is why screening is recommended from age 50
Family history: a parent, brother, sister or other second degree relative who has had colorectal cancer or a colon polyp
Personal history: previous colorectal polyps, colorectal cancer or ovarian cancer
Inherited conditions: such as Lynch syndrome and familial adenomatous polyposis (FAP)
Bowel conditions: long standing ulcerative colitis or Crohn's disease
Lifestyle: heavy alcohol use, smoking and obesity

Having one or more risk factors does not mean you will develop colorectal cancer, and some people with no known risk factors still do.

Types of Colorectal Cancer

Colorectal cancer is described by where it starts, and this affects how it is treated.

Colon Cancer

Colon cancer develops in the colon, the part of the large intestine that reabsorbs fluids and processes waste from the body. Surgery to remove the tumour is the mainstay of treatment, with chemotherapy added depending on the stage.

Rectal Cancer

Rectal cancer develops in the rectum, the final section of the large intestine before the anus. Because rectal tumours tend to return near where they first formed, treatment often combines chemotherapy and radiation therapy with surgery.

Hereditary Colorectal Cancer

Some colorectal cancers are linked to inherited conditions such as Lynch syndrome and FAP. People whose family history suggests an inherited condition may be advised to have a genetic risk assessment.

Stages of Colorectal Cancer

Doctors use the tumour, node and metastasis (TNM) system, which looks at how far the tumour has grown, whether nearby lymph nodes are affected and whether the cancer has spread to other parts of the body. A stage from 0 to IV is then assigned, and this is the standard used in Malaysian histopathology reporting.

Stage 0: abnormal cells are only on the innermost layer of the lining of the bowel
Stage I: the cancer is in the inner layers of the bowel wall
Stage II: the cancer has grown through the muscle wall of the bowel
Stage III: the cancer has spread to nearby lymph nodes
Stage IV: the cancer has spread to other organs, such as the liver or lungs

How to Collect Your FOBT Sample

The faecal occult blood test (FOBT) is a simple, non invasive stool test that checks for hidden blood, and it can be done at home. At Sunway Medical Centre Penang, collecting your sample takes three steps:

1. Prepare

Check your name and date of birth on the label
Clean your hands with soap and water

2. Collect

Pass stool onto a clean plastic sheet or dry container
Use the attached spoon to take a peanut sized amount (2 to 3 scoops)
Do not mix the sample with urine or toilet water

3. Seal and Pack

Screw the cap on tightly
Place the bottle into the biohazard or ziplock bag
Wash your hands thoroughly

4. Return

Submit your sample within 2 hours of collection to the Health Screening Centre (Level 2), Sunway Medical Centre Penang
Your results will be ready within 7 working days and sent to you by email

Colorectal Cancer Diagnosis

Our doctors at the Cancer Centre decide which tests are needed based on your symptoms, the type of cancer suspected, your age and your medical history.

Colonoscopy

A colonoscopy allows the doctor to look inside the entire rectum and colon using a thin, flexible tube with a camera, usually while you are sedated. Polyps found during the procedure can be removed and examined.

Biopsy

A biopsy removes a small amount of tissue to be examined under a microscope. Other tests may suggest that cancer is present, but only a biopsy can make a definite diagnosis of colorectal cancer.

Scans and Blood Tests

If colorectal cancer is diagnosed, CT or MRI scans of the abdomen, pelvis and chest may be used to see whether it has spread, and PET scans are sometimes added. Blood tests such as carcinoembryonic antigen (CEA) may help monitor your progress during and after treatment.

Colorectal Cancer Treatment Options

At Sunway Medical Centre Penang, a multidisciplinary team from the Cancer Centre works together to create a treatment plan suited to each patient.

Surgery

Surgery, also called surgical resection, is the mainstay of treatment for colorectal cancer. The tumour and some surrounding healthy tissue are removed during the operation. Very early stage 0 cancer may be removed through a colonoscopy.

Surgical options include robotic surgery, laparoscopic surgery and traditional open surgery. With robotic or laparoscopic surgery, three or four small cuts are made, which allows quicker recovery and less blood loss. With open surgery, a larger cut is made in the abdomen, which usually means a longer hospital stay and slower recovery.

Robotic Surgery

Laparoscopy Surgery

Chemotherapy

Chemotherapy uses medicines to kill cancer cells. It is usually given in cycles, with a rest period between treatments so your body can recover. It may be given after surgery to remove any remaining cancer cells. For rectal cancer, chemotherapy and radiation therapy are often given before surgery to reduce the size of the tumour and the chance of the cancer returning.

Radiation Therapy

Radiation therapy uses high energy X rays to destroy cancer cells. It is commonly used for rectal cancer because tumours tend to return near where they first formed. Patients may receive external radiation, internal radiation, intraoperative radiation therapy (IORT), or a combination.

Side effects depend on the radiation dose and the part of the body treated. They can include nausea, vomiting, diarrhoea, bloody stools, urgent bowel movements, and urinary and skin sensitivity problems.

Other treatments, such as targeted therapy and immunotherapy, may also be considered in selected cases.

Prevention and Early Detection

Screening looks for polyps or early cancer before any symptoms appear. The Ministry of Health Malaysia clinical practice guideline recommends the following:

Screening should be offered from age 50 and continue until age 75 for people at average risk
The immunochemical faecal occult blood test (iFOBT), also known as the faecal immunochemical test (FIT), is the preferred screening method
If the test is negative, it should be repeated every year. If it is positive, a colonoscopy is needed
People with a family history of colorectal cancer should be screened, and those whose family history suggests an inherited condition should be referred for genetic risk assessment

Packages and Promotion

Free Colorectal Cancer Screening

: English, Bahasa Malaysia

Dr. Saidah Sahid is a consultant general and colorectal surgeon at Sunway Medical Centre Penang, with both fellowship and working experience in colorectal surgery in the UK. Patients can meet Dr. Saidah for assessment of conditions affecting the colon and rectum.

When Should You See a Colorectal Specialist?

You notice blood in your stool
Your bowel habits have changed and the change is not going away
You have unexplained weight loss or ongoing abdominal pain
You are 50 or older and have never been screened
A close relative has had colorectal cancer, or you know of an inherited condition in your family
You have been diagnosed with colorectal cancer and would like to discuss your treatment options or seek a second opinion

Seeing a specialist does not mean you have cancer. It means finding out where you stand and having a plan. Speak with our colorectal surgeons at Sunway Medical Centre Penang to understand your condition and the options available to you.

Learn more about cancer care at our Cancer Centre in Penang

Frequently Asked Questions

Does blood in the stool always mean colorectal cancer?

No. Blood in the stool can also be caused by conditions such as piles (haemorrhoids), infections or inflammatory bowel disease, many of which are much less serious than cancer. However, because these causes can look the same as colorectal cancer, blood in the stool or a lasting change in your bowel habits should always be checked by a doctor rather than assumed to be piles.

What is the difference between a FIT test and a colonoscopy?

A FIT test is a stool test that picks up tiny traces of blood you cannot see. It does not diagnose cancer by itself, but a positive result means a colonoscopy is needed. A colonoscopy examines the whole colon and rectum directly, and polyps found during the procedure can be removed at the same time.

Can I lower my risk of colorectal cancer?

Some risk factors cannot be changed, but avoiding heavy alcohol use, not smoking and keeping a healthy weight are linked to a lower risk. Regular screening remains important even if you live a healthy lifestyle, because it can find polyps before they become cancer.

Is colorectal cancer hereditary?

Some cases are. Inherited conditions such as Lynch syndrome and familial adenomatous polyposis raise the risk, and a close relative with colorectal cancer also increases yours. If your family history suggests an inherited condition, the Ministry of Health guideline advises referral to a clinical genetics service for genetic risk assessment. Our Genetic Services team at Sunway Medical Centre Penang offers genetic counselling and genetic testing.