Through the media, we have heard about the number one cancer in Singapore – colorectal cancer, which refers to the cancer of the colon or rectum. Due to the high prevalence of this disease, we may probably know of someone diagnosed with colorectal cancer. According to a survey from the Ministry of Health taken between 2013 to 2017, colon cancer is the most common cancer in males and the second most common in females.

What is Colorectal Cancer?

But what are the colon and rectum? And what are their functions as part of human anatomy? The colon or large intestine is part of the digestive system that comes after the stomach and small intestines. Its role is to dehydrate food remnants and turn them into waste. The colon does this by absorbing water and electrolytes as its muscle system moves the waste along. Concurrently, gut flora residing in the colon feed on the waste and break it down further, completing the chemical part of the digestive process. The colon continues as the rectum, which serves to store the stools before elimination from the body.

Colorectal cancer occurs when cells in the colon or rectum grow out of control. This unregulated cell growth can lead to the formation of tumours that can obstruct the bowel, causing symptoms like irregular bowel movements, bleeding, and abdominal pain. Over time, these cancerous cells can also invade other tissues and spread to different parts of the body.

What Are The Stages of Colorectal Cancer? 

Colorectal cancer can manifest at various stages, each with distinct characteristics. These stages, ranging from 0 to IV, provide crucial information about the extent of cancer spread and guide treatment decisions.

Knowing the stage of your cancer empowers you to understand the situation better and work with your doctor to develop the most effective treatment plan. Here's a breakdown of the five main stages of colorectal cancer:

• Stage 0: This is the earliest stage, where abnormal cells are present only in the innermost lining of the colon or rectum (in situ carcinoma).
• Stage I: The cancer has grown through the inner lining (musoca) but has not spread outside the colon or rectum.
• Stage II: The cancer has grown through the inner lining of the colon or rectum wall and may have spread to nearby lymph nodes.
• Stage III: The cancer has spread to several nearby lymph nodes but not to distant organs.
• Stage IV: The cancer has metastasized (spread) to distant organs such as the liver or lungs.

What Causes Colon Cancer?

The abnormal growth of cells in the colon can be triggered by a variety of factors. These range from genetic predispositions to environmental influences and existing health conditions, each playing a part in increasing the risk of developing colon cancer. Causes of colon cancer include:

• Genetic mutations: Changes in certain genes that control cell growth can be inherited or develop over time, making cells more likely to become cancerous.
• Dietary factors: A diet high in red and processed meats and low in fibre has been linked to an increased risk of colorectal cancer.
• Lifestyle choices: Lack of physical activity, obesity, smoking, and heavy alcohol use have all been shown to contribute to the risk.
• Old age: The risk of developing colon cancer increases significantly after the age of 50.
• Inflammatory bowel diseases: Conditions like Crohn’s disease and ulcerative colitis can increase the risk due to chronic inflammation in the colon.
• Smoking and alcohol consumption: Smoking and heavy alcohol use can damage the cells in your colon, increasing the risk of cancer.
• Sedentary lifestyle: Lack of physical activity can contribute to the onset of colon cancer. An estimated 12-14% of colon cancer could be attributed to lack of frequent involvement in vigorous physical activity.
• Obesity: Excess body fat in the body may impact natural functions like blood vessel growth and hormone levels, increasing the risk of developing several cancers, including colon cancer.
• Polyps: Having a history of colon polyps, which are benign growths in the colon, can increase your risk of developing colorectal cancer if not removed.
• Cancer history: A personal history of certain cancers, such as endometrial cancer or ovarian cancer, can increase your risk of colon cancer.
• Family history: Having a close relative (parent, sibling, or child) with a history of colorectal cancer increases your risk.

Colon Cancer Signs and Symptoms

In a bid for early colon cancer detection, it is important to be aware of the signs and symptoms of colorectal cancer so that appropriate medical advice can be rendered. These signs and symptoms include:

• Frequent abdominal pain or bloating
• Changes in bowel habits such as diarrhoea and constipation
• Blood in stool
• Anaemia
• Unexplained weight loss
• Weakness and fatigue
• Fever and pain

If one or more symptoms are persistent and/or progressive, it is time to seek help from a physician.

Who’s at high risk of contracting colorectal cancer?

Your risk of getting colorectal cancer increases as you get older. Other notable risk factors include:

• Inflammatory bowel disease such as Crohn’s disease
• Family history of colon cancer or colorectal polyps
• Hereditary non-polyposis colon cancer (Lynch syndrome)
• Familial adenomatous polyposis (FAP)
• Consumption of processed meat and red meat
• Consumption of meat cooked at high temperatures
• Alcohol consumption
• Tobacco use

Prevention Tips for Colorectal Cancer

Just how can we prevent colon cancer then? A key component in prevention is making lifestyle changes and consistently maintaining a healthy lifestyle. It is not an easy feat to make lifestyle changes, so try to make them gradually, and progressively work towards your goal over a period of time.

1. Incorporate High-Fibre Foods Into Your Diet

One important lifestyle change to make is adopting a well-balanced diet that includes plenty of fruits and vegetables, protein, carbohydrates, and healthy fats. Focus on foods high in fibre and complex carbohydrates while minimising saturated and trans fats. Excellent sources of fibre include:

• whole grains
• legumes
• vegetables such as green peas, broccoli, and turnip greens,
• fruits like raspberries, pears, and apples.

Ensuring high fibre intake is essential as it can reduce the risk of colon cancer by increasing stool bulk, diluting carcinogens found in the stool, and speeding up the movement of stool through the colon, thus reducing contact time between carcinogens and the colon lining.

2. Minimise Red Meat Consumption

Avoid consumption of red meats and processed meats (such as ham, bacon, sausages, smoked or salted meats). These foods can possibly increase the risk of colorectal cancer due to their processing and cooking methods.

The compounds formed during processing or cooking at high temperatures can damage colon cells, potentially leading to cancerous mutations. Additionally, red meat contains heme iron, which may promote the formation of potentially carcinogenic compounds in the digestive tract.

3. Adopt a More Active Lifestyle

Another lifestyle factor that may contribute to the decrease of colon cancer risk is regular physical activity. Incorporating mild to moderate exercise or other forms of physical activity for at least 150 minutes a week can be beneficial. As a bonus, regular exercise also has a host of other benefits that are good for your heart, body, and mind.

As with any lifestyle change, ease into it slowly and progressively to increase the likelihood of sustaining the habits. If you encounter any side effects from these changes, be sure to consult a physician.

4. Avoid Alcohol and Tobacco

Reduce alcohol consumption and avoid cigarette smoking. Alcohol can damage colon and rectal cells, making them more susceptible to cancer. Similarly, the carcinogens in tobacco smoke can directly contribute to colon cancer by inducing DNA mutations that lead to cancerous growth.

Screening for Colon Cancer

Cancer screening refers to the process of looking for pre-cancer or early-stage cancer in people who do not exhibit any symptoms of the disease. This means screening can help diagnose those with early-stage colon cancer to increase the chance of successful colon cancer treatment.

Individuals without risk factors should begin screening at the age of 45, while those with a high risk of colon cancer should begin earlier than 45. A physician will be able to advise when to begin; it might be earlier than required should there be risk factors present, as well as the frequency of screening.

Faecal Immunochemical Test (FIT)

Colorectal cancer screening can be done through a faecal immunochemical test (FIT) to detect the presence of trace amounts of blood in stool which may not be visible to the naked eye. Low-risk individuals aged 45 and above are encouraged to do a FIT annually.

Colonoscopy

Another form of screening is a colonoscopy. This is a medical procedure that allows the physician to view your large intestine with a colonoscope that is fitted with a camera and light. Colonoscopy is a vital part of colon and rectal cancer prevention as aenomatous polyps can be detected and removed during this procedure. These polyps are responsible for the majority of colorectal cancers and are largely asymptomatic and transform into cancer over a long time.

Moreover, during colonoscopy, cancers which have already developed within the colon and rectum can be identified early, allowing for treatment at an earlier stage, leading to higher cure rates. A colonoscopy can also be performed together with a gastroscopy to screen for colon and stomach cancer.

Virtual colonoscopy is one other new technique to consider for cancer screening. It is carried out through a CT scan. However, due to its non-invasive nature, this procedure cannot be used to remove polyps.

Seek Early Treatment And Care

The main focus to prevent colorectal cancer is early detection and treatment. Here at OncoCare, our team of oncologists, consultants, and cancer specialists in Singapore are here to help with accurate tests, workups, and a full diagnosis among our oncology services. With experience in diagnosing and treating colon and rectal cancer, we are able to advise on the optimal treatment options.

At OncoCare, personalised care is at the forefront with colorectal treatment plans personalised for each individual patient. Find out how we can help, learn more about cancer treatments in our patient education blog, and reach out to us to make an appointment online or call us at +65 62508160.

“Expert knowledge means better care for cancer”

Written by:
Dr Wong Nan Soon
MBBS (Singapore)
M.Med (Singapore)
MRCP (United Kingdom)
FAMS (Medical Oncology)
MHsc (Duke, USA)