Colorectal Cancer

What is Colorectal Cancer?

Colorectal cancer is the most common cancer in Singapore. In fact, 1 in 20 people is more likely to develop colorectal cancer during their lifetime. Additionally, roughly 1,500 new cases are reported annually.

Colorectal cancer, also known as colon or bowel cancer, is a type of cancer that develops in the colon or the rectum. It typically begins as a polyp growth, which may start as benign but progresses into cancerous over time.

It is usually classified based on the extent of its spread (stage). The stages of colorectal cancer are:

• Stage 0: in the initial stage, also known as carcinoma in situ, the cancer cells are only in the innermost layer of the colon or rectum lining and have not spread.
• Stage I: the cancer has grown through the mucosa (inner lining) into the submucosa (next layer) but has not spread beyond the colon or rectum wall.
• Stage II: the cancer has grown through the muscle layer of the colon or rectum but has not spread to nearby lymph nodes or other organs.
• Stage III: the cancer has spread to nearby lymph nodes but not to the distant organs.
• Stage IV: the cancer has spread to distant organs, such as the liver, lungs, or other distant sites, beyond the colon or rectum.

What causes colorectal cancer?

DNA within each cell guides its normal functions, such as growth regulation, division, and programmed cell death. However, disruptions can occur when mutations arise within the DNA, causing cells to grow uncontrollably and evade the body's natural mechanisms for cell death. Over time, these abnormal cells accumulate, forming a mass or tumour within the colon. 

Unfortunately, doctors are unable to determine one exact cause of why DNA mutations occur. It is usually due to multiple factors. Most colorectal cancer cases originate from adenomatous polyps, which are growths that develop within the lining of the colon wall. Although these polyps mostly start as benign, they can become malignant.

What are the symptoms of colorectal cancer?

As with most cancer cases, colorectal cancer usually does not produce any symptoms in its early stages. But as the cancer progresses, symptoms of colon cancer include:

• Changes in bowel habits: changes in bowel habits, such as diarrhoea, constipation, alternating diarrhoea and constipation or a change in the consistency or calibre of stools, may occur. This includes a feeling of incomplete emptying after a bowel movement.
• Rectal bleeding: one of the most common symptoms of rectal cancer is rectal bleeding. This may be bright or dark red and indicates bleeding from a tumour in the colon or rectum.
• Unintentional weight loss: colon cancer can affect the body’s metabolism and nutrient absorption, resulting in weight loss.
• Anaemia: individuals with colon cancer may become anaemic. This is due to chronic bleeding from the tumour, resulting in symptoms such as fatigue, weakness, and pale skin.
• Abdominal pain or cramping: persistent abdominal discomfort, cramping, bloating, or pain may occur, often in the lower abdomen.
• Nausea and vomiting: persistent nausea, vomiting, or a feeling of fullness in the abdomen may occur, particularly if the tumour is obstructing the bowel or causing other digestive issues.

Who is at risk of developing colorectal cancer in Singapore?

Several factors can increase an individual's risk of developing colorectal cancer; these are:

• Age: the risk of colorectal cancer increases with age, with the majority of cases diagnosed in individuals over the age of 50. However, recent years have shown an increase in the incidence of colon cancer in individuals below the age of 50.
• Family history: individuals with a family history of colon cancer and other related polyps are at an increased risk of developing colorectal cancer.
• Inflammatory bowel disease (IBD): individuals with IBD are at an increased risk of colon cancer. Inflammation over time can lead to changes in the lining of the colon or rectum, increasing the risk of cancerous growth.
• Genetic conditions: genetic conditions such as Lynch syndrome (HNPCC), familial adenomatous polyposis (FAP), and MUTYH-associated polyposis (MAP) increase the risk of colon cancer.
• Obesity and sedentary lifestyle: being obese and leading a sedentary lifestyle increases the risk of developing colorectal cancer. 
• Low-fibre diet: a diet high in red and processed meats, saturated fats, and low in fibre, fruits, and vegetables may increase the risk of colorectal cancer.
• Smoking and alcohol consumption: tobacco smoking and heavy alcohol consumption have been linked to an increased risk of colorectal cancer. 

How is colon cancer diagnosed?

Colon cancer is diagnosed using a combination of the following:

• Medical history and physical examination: your specialist will begin by taking a thorough medical history, including any symptoms the individual may be experiencing, personal and family medical history, and risk factors for colon cancer. A physical examination, including a digital rectal examination, may also be performed to assess for abnormalities.
• Stool tests: a faecal occult blood test and a faecal immunochemical test may be conducted to check for the presence of blood in stools. 
• Blood test: a blood test may be conducted to check for signs of anaemia. 
• Colonoscopy: a colonoscopy is considered the gold standard for diagnosing colon cancer. During this procedure, a long, flexible tube with a camera (colonoscope) is inserted into the rectum and advanced through the colon. The colonoscope allows the healthcare provider to visualise the inside of the colon and rectum, identify abnormalities, and obtain tissue samples (biopsies) for further evaluation.
• Imaging studies: imaging tests such as magnetic resonance imaging (MRI), computed tomography (CT) scans, and positron emission tomography (PET) scans can identify if the cancer has metastasised.

What are the treatment options for colorectal cancer in Singapore?

Treatment will usually begin soon after a colorectal cancer diagnosis has been confirmed. However, the course of treatment heavily depends on how advanced the cancer is and your medical history. The common treatment options for colorectal cancer include:

• Surgery: a surgical intervention is often the primary treatment for colorectal cancer in Singapore. However, the type of surgery may depend on the tumour's size and location. Some of the surgical options for colorectal cancer include:
  • Colectomy, where a portion of the cancerous colon is removed.
  • Polypectomy, where the cancerous or precancerous polyps are removed.
  • Rectal resection (Anterior Resection), where a portion or the whole of the rectum is removed.
• Chemotherapy: chemotherapy uses drugs to kill cancer cells and prevent them from growing. 
• Radiation therapy: radiation therapy uses high-energy beams to destroy cancer cells or shrink the tumour pre-surgery.
• Targeted therapy: targeted therapy drugs target specific abnormalities within the cancer cells, such as mutations or proteins that stimulate cancer growth.

Book an appointment today to learn more about our treatment plans at Lee Surgery & Endoscopy.

Frequently asked questions

What are the first signs of colon cancer?

Colorectal cancer often does not cause symptoms in its early stages, which is why regular screening is crucial for early detection and treatment. Once symptoms occur, the cancer is typically in the more advanced stages, and symptoms include rectal bleeding, bloating, changes in bowel habits, fatigue, unexplained weight loss, anaemia, nausea, and vomiting.

Can colon cancer be cured?

Colon is highly curable as long as the cancer has not metastasised and stays localised to the colon. While colon cancer can be a serious and potentially life-threatening disease, it is often curable, especially when detected early.

What can I do to prevent colon cancer?

Firstly, it is important to adopt a healthier lifestyle rich in fibre-rich foods and exercise. Going to regular screenings is highly recommended, especially if you have a family history of colorectal cancer or polyps.