Colorectal Cancer

– The information has been reviewed by Dr. Yang Pei Cheung, George

Current Statistics of Colorectal Cancer

According to the statistics by the Hong Kong Cancer Registry of the Hospital Authority, colorectal cancer has the highest incidence rate amongst the 10 most common cancers in Hong Kong in 2017, reaching a high of 5,635 cases. The mortality rate of colorectal cancer ranked second, showing an increased incidence in recent years.


What is colorectal cancer?

The large intestine comprises the colon and rectum, and its main function is to absorb water and store feces. Studies have found that colorectal cancer originates from the growths on the inner lining of the colon and rectum, which are called adenomatous polyps. Despite the polyps being benign, they can become malignant over time with gene mutation. This nature of colorectal cancer makes it one of the few preventable cancers.


Early stages of colorectal cancer might have no obvious symptoms, and it is difficult for patients to notice if they have any polyps in their intestines. Therefore, patients with obvious symptoms are often in their third stage at the time of diagnosis.

  • Blood in stool or stool that looks dark brown or black
  • Mucus in stool
  • A change in bowel habits (constant diarrhea or constipation)
  • Weight loss
  • Persistent abdominal discomfort
  • A feeling that your bowel doesn't empty completely
  • Symptoms of anemia such as cold hands and feet, fatigue, elevated heart rate, shortness of breath, pale complexion, etc.
Causes & Risk Factors
Causes & Risk Factors

Colorectal cancer mainly evolves from polyps. Amongst the different types of polyps, adenoma is a type that can be prevented as its growth is mainly associated with eating diets of high animal fat, high protein, and low fiber. Therefore, maintaining a healthy diet can help reduce the risk of developing colorectal cancer.


Risk Factors

  • Men
  • Age: People who are 50 or above
  • Chronic inflammation in the intestines, such as Crohn’s disease
  • Family history of colorectal cancer
  • Smoking
  • Excessive drinking
  • Obesity
  • Lack of exercise
  • low-fiber diet or high-fat diet
How is colorectal cancer diagnosed?
How is colorectal cancer diagnosed?
  • Regular screening: It takes about 7 to 10 years for colorectal polyps to develop and grow into cancer. Therefore, it is recommended to take regular screenings such as fecal occult blood test (FOBT) and colonoscopy from the age of 45 to 50.
    • A fecal occult blood test is used to detect blood in stool that is not noticeable to the naked eye. If blood is present in the stool, the patient will be arranged to undergo a colonoscopy for a detailed examination and removal of polyps for laboratory tests. If only a small amount of polyps is found and they are benign, the patient can take another colonoscopy after 5 years; if more than 20-30 polyps are detected during the exam, the patient should undergo another colonoscopy the next year.
    • However, just fecal occult blood test (FOBT) alone cannot be used to determine if the patient has colorectal cancer. Since most polyps do not cause bleeding, the absence of blood in stool does not necessarily mean colorectal cancer tumor is absent. This is the reason why doctors would still recommend colonoscopy after reviewing their cases, even though their fecal occult blood test came out to be negative.
  • Imaging tests: Imaging tests such as PET scan, computed tomography (CT) or  magnetic resonance imaging (MRI) can help determine the size and location of the cancer, surrounding structures involvement, and also if there is any metastatic lesion.
Stages of Colorectal Cancer
Stages of Colorectal Cancer
Stages Five-year survival rate

Stage 1: Cancer cells are only found on the intestinal wall and have not metastasized.


Stage 2: Cancer cells have grown into the outermost layers of the colon or rectum but have not gone through these layers. When cancer cells grow through the outermost layers, this could affect other organs. At this stage, cancer cells have not spread to lymph nodes or other parts of the body.


Stage 3: Cancer cells metastasize to the surrounding lymphatic system.


Stage 4: Cancer cells have spread to distant sites such as the liver and lungs.



Treatment of Colorectal Cancer
Treatment of Colorectal Cancer
  • Surgery is still the main state and most effective treatment for cancer of the colon. By removing the main cancer, it prevents future bowel obstruction by the cancer and improves the function of the colon. And also the surgical resected tumor will be sent for microscopic examination of the cancer itself and lymph node involvement if there is any, thereby giving us the exact staging of the diseases.

    Advanced Technology for the Treatment of Colorectal Cancer

    • The da Vinci Robotic Arm Surgery: This is the most cutting-edge minimally invasive technology for the treatment of colorectal cancer. Through high-resolution three-dimensional images produced by the da Vinci system, doctors can accurately determine the location of the tumor during the surgery. The robotic wrist is flexible and has a wide range of movement. Robotic system filter out any hand tremor which allows more precise and accurate movements than traditional minimally invasive surgery. Even for tumors that are located at the deepest part of the pelvis or the narrowest part of the rectum, the da Vinci Robotic arm can help remove the tumor in a precise manner without damaging the surrounding nerves. With the da Vinci technology, the risk of urinary complications can also be reduced, improving the treatment effect and patient safety.
    • Tomotherapy: The system can deliver radiation to the tumor from a 360-degree rotation, delivering precise doses of radiation to different parts of the tumor to reduce the damage to the small intestine that is in constant peristalsis as well as other organs.
    • Preoperative chemotherapy: For advance cancer in the rectum, the patient will undergo chemotherapy or radiotherapy before having the cancer tumor removed by surgery. This aims to shrink the size of the tumor before surgery, which could provide a wider surgical margin in the patient’s abdominal cavity for clean tumor removal.