Colon Cancer

Colorectal cancer is the most common cancer among males and 2^nd most common cancer among females in Singapore.

Regular screening tests such faecal occult blood test and colonoscopy can help prevent colon cancer.

Colon cancer is cancer of the large intestine (colon) and rectal cancer is cancer of the last 6 inches of the colon which are often referred to as colorectal cancers.

Most cases of colon cancer begin as non-cancerous (benign) polyps which can become cancerous over time. Polyps can appear mushroom-shaped or some can be flat recessed into the wall of the colon.

Common types of intestinal polyps include:

• Adenomas.
• Hyperplasic polyps.
• Inflammatory polyps following a bout of ulcerative colitis.

Symptoms

In the early stages, people with colon cancer may not experience any symptoms.

In the latter stages, the common signs and symptoms include:

• A change in the bowel habits, including diarrhea or constipation
• Rectal bleeding or blood in the stool
• Persistent abdominal discomfort such as cramps, gas or pain
• Abdominal pain with a bowel movement
• Incomplete emptying of the bowel
• Weakness or fatigue
• Unexplained weight loss

Causes

As with most cancers, the exact cause for colon cancer is unknown.

Experts believe that it is multi-factorial involving a combination of genetic and environmental factors.

Risk factors

Factors that may increase the risk of colon cancer include:

• Age: common in persons>50 years
• Inflammatory intestinal conditions: Ulcerative colitis and Crohn’s disease.
• Inherited disorders: familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC), also called Lynch syndrome.
• Family history of colon cancer and colon polyps.
• Diet low in fibre and high in fat and calories.
• Sedentary lifestyle, diabetes, obesity and smoking.
• Acromegaly that causes an excess of growth hormone may increase the risk of colon polyps and colon cancer.
• Radiation therapy for cancer directed at the abdomen to treat previous cancers.

Diagnosis

See your doctor as soon as possible if you have:

• Blood in your stool
• A persistent change in bowel habits

Common screening tests include:

• Stool blood test (Faecal Occult Blood Test)

Other tests include:

• Flexible Sigmoidoscopy
• Barium enema is used to evaluate your entire large intestine with an X-ray with barium.
• Colonoscopy.

Treatment

The three primary treatment options are: surgery, chemotherapy and radiation which may be used alone or in combination.

Surgical options include:

• Colectomy

  Includes removal of the colon that contains the cancer.
  
  

• Chemotherapy

  Chemotherapy can be used to destroy cancer cells after surgery, to control tumor growth or to relieve symptoms of colon cancer. Possible side effects of chemotherapy include:
  • Nausea and vomiting
  • Mouth sores
  • Fatigue
  • Hair loss and diarrhoea

• Radiation therapy

  Radiation therapy uses X-rays to kill any cancer cells that might remain after surgery, to shrink large tumors before an operation so that they can be removed more easily, or to relieve symptoms of colon cancer and rectal cancer. Side effects of radiation therapy may include:
  • Diarrhea
  • Rectal bleeding
  • Fatigue

Screening

Regular colon cancer screening should begin at age 50 for people who have no symptoms. The screening options would include fecal occult blood testing annually.

For those at high risk of colon cancer such as those with family history of colorectal cancer in first degree relatives, inherited disorders such as familial adenomatous polyposis and Hereditary Non Polyposis Colorectal cancer, the screening options include:

• Annual fecal occult blood testing
• Flexible sigmoidoscopy
• Colonoscopy

Discuss with your doctor regarding the best screening option for youand the frequency of testing.

Prevention

You can also take steps to reduce the risk of colon cancer by:

• Eating plenty of fruits, vegetables and whole grains which contain fiber and antioxidants.
• Limiting fat especially saturated fat from animal sources such as red meat, milk, cheese, ice cream, and coconut and palm oils.
• Limiting alcohol intake.
• Quitting smoking.
• Staying physically active and maintaining a healthy body weight.