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Colorectal Cancer Screening, Diagnosis and Treatment

Colorectal cancer is the most common cancer and second leading cause of cancer deaths in Hong Kong. According to the latest statistics from Hong Kong Cancer Registry, there were 5,437 new cases of colorectal cancer in 2016, with 2,089 deaths caused by colorectal cancer[1]. Unlike most of the high-risk cancers, colorectal cancer can be prevented by regular colorectal cancer screening. Jointly issued by the U.S. Preventive Services Task Force which represents the American College of Gastroenterology, the American Gastroenterological Association and The American Society for Gastrointestinal Endoscopy, the colorectal cancer screening recommendations[2]outline that people at average risk of colorectal cancer should initiate routine colorectal cancer screening beginning at age 50. Early detection and removal of precancerous lesions has been proven to significantly reduce the chances of developing colorectal cancer[3].

For most colorectal cancers, surgery is the primary and most effective treatment. Below is the latest information about colorectal cancer treatment and options overview, including colorectal cancer screening, diagnosis and treatment as well as frequently asked questions.

What Is Colorectal Cancer?

The intestines include the small intestine and large intestine. Colon and rectum are parts of the large intestine and therefore, colon cancer and rectal cancer are also known as colorectal cancer. As both colon cancer and rectal cancer begin when polyps on the inner surface of the large intestine grow cancerous, removing these polyps will reduce the risk of developing colorectal cancer[4]. Unfortunately, colorectal cancer may occur without symptoms at the early stage. In the event when symptoms do occur, they may include chronic constipation and diarrhea, blood on or in the stool and unexplained weight loss.

Symptoms of colorectal cancer


If you experience the following ?colorectal cancer symptoms for a period of time, you should consult a doctor as soon as possible:

  1. A persistent change in bowel habits (such as constipation or diarrhea)
  2. Abdominal discomfort
  3. Constant fatigue or weakness
  4. Dark stools or blood in the stool
  5. Iron deficiency
  6. Weight loss

Colorectal Cancer Risk Factors


There are a number of risk factors that might increase a person’s chance of developing colorectal cancer, for example, unhealthy lifestyles and diet habits. They are not only two of the most common risk factors of colorectal cancer but also contribute to an increase in colorectal cancer in young adults. Below is a list of factors that may influence the risk of developing colorectal cancer:

  1. A family history of colorectal cancer*
  2. Colorectal polyps
  3. Being older – 90% of colorectal cancer patients are aged 50 or above[5]
  4. Certain types of diets – a diet that is insufficient in fiber consumption or high in red meats, processed meats and fats raises your colorectal cancer risk
  5. Inflammatory bowel disease – such as ulcerative colitis and Crohn’s disease
  6. A personal history of colorectal polyps or colorectal cancer

*Some family cancer syndromes will significantly increase the risk of colorectal cancer, including:

Familial adenomatous polyposis (FAP): ?the likelihood of patients with FAP to develop colorectal cancer before the age of 50 can be up to 93%[6]

Lynch syndrome (hereditary non-polyposis colon cancer or HNPCC): approximately 80% of patients with HNPCC will develop colorectal cancer before the age of 70[7]

Colorectal Cancer Screening Options

At HKIOC, we provide a wide range of colorectal cancer screening tests, including:

stool test

Fecal Occult Blood Tests (immunohistochemical test)

It is recommended to anyone without colorectal cancer symptoms as an initial screening option. The test checks for occult (hidden) blood in the stool by collecting a small sample of stool[8].

ct colonography

Computed Tomographic Colonography (CT)

It is a less invasive screening option that uses a CT scanner to produce a series of pictures of the colon and the rectum from outside the body. ?If polyps or other abnormal growths are identified during a virtual colonoscopy, patients will be recommended to undergo a standard colonoscopy for a thorough assessment.

colonoscopy and thin tube with camera

Standard (or optical) colonoscopy

People at high risk of colorectal cancer or with suspicious polyps or other abnormal growths identified during an initial screening are recommended to have a standard colonoscopy. In this test, the inner lining of large intestine (rectum and colon) is examined using a colonoscope-a thin and flexible tube with a lens for viewing. The colonoscope is inserted through the anus and advanced to the other end of the large intestine. During a colonoscopy, the physician can remove any abnormal growths in the colon and the recutum, and collect tissue samples for a more detailed analysis.



Sigmoidoscopy is similar to colonoscopy, and is a procedure for examining using a thin and flexible tube with a lens. Sigmoidoscopy covers only the lower part of the colon, examining the rectum and sigmoid colon. Since a sigmoidoscopy only looks at part of the colon, the risk is relatively lower as a medical procedure.

People at high risk of developing colorectal cancer should consult their doctors and consider starting screening at an earlier age (for example, 40, compared with an average risk of 50).

Colorectal Cancer Treatment

Before deciding on a colorectal cancer treatment option, patients are required to perform a full body check-up, including Magnetic Resonance Imaging (MRI) and Positron Emission Tomography/Computed Tomography (PET-CT), for a thorough analysis of the cancer stage. Below are the latest colorectal cancer treatment options:

1.Traditional Colorectal Cancer Surgery

Once patients are diagnosed with colorectal cancer, surgery is the most effective treatment. Doctors will perform minimally-invasive surgery on patients to remove the identified cancerous tissues and surrounding tissues, and examine whether the cancer cells have spread to the lymph nodes. Normally, patients will recover in a short period of time without seriously interrupting their daily lives. Take colon cancer as an example, colon cancer surgery usually involves the removal of a small part of the intestines. And the ends of the intestines can be reconnected without significantly affecting digestive functioning.

However, if the surgery involves the removal of anus and rectum, patients may need to undertake additional surgeries such as colostomy or ileostomy which create a permanent or temporary stoma in the body, an artificial opening that allows waste (faeces or urine) to be diverted out of the body. Currently available stomas are very advanced; they are firmly attached to the skin and come with deodorizer to ensure minimum inconvenience for swimming and when doing other sports. However, given that having a stoma can take a drastic psychological toll on the patients, it should be avoided unless absolutely necessary.

2.Transanal Total Mesorectal Excision (TaTME)

This procedure removes rectal cancer using an instrument inserted to the anus. This surgical technique is still in its developmental stage and requires more clinical evidence to demonstrate the benefits, but it has been gaining popularity worldwide and has been adopted in Hong Kong as one of the colorectal cancer treatments.

3.“Watch-and-Wait” Approach

In individual cases that involve the tumor in the lower parts of the intestines, which is 5cm or below close to the anus, traditional colorectal cancer surgeries normally remove the anus and sphincter, creating in the body a permanent or temporary artificial opening to where the flow of waste will be discharged. The “Watch-and-Wait” treatment approach, on the other hand, applies chemotherapy and radiotherapy before the operation aiming to reduce the size of the tumor, delay and even avoid surgery so that the patients can discharge digestive waste materials from their body as they normally do.

In the first year of treatment, patients are required to undertake at least seven MRIs. After that, patients will also need to receive MRI screenings and colonoscopy on a regular basis so medical staff can closely monitor their recovery. Approximately 30% of the patients with colorectal cancer are reported to have cancerous cells completely disappeared using the “Watch-and-Wait” treatment method. Although the risk of recurrence is 50%, 90% of patients who suffer recurrence can still be cured with surgery.

4.Targeted therapy for late-stage colorectal cancer

In the past, there were limited treatment options for late-stage colorectal cancer. Thanks to medical advancement, there are now more than ever new ways to treat patients with late-stage colorectal cancer, allowing them to live longer than three years on average. Doctors will advise treatment plans according to the patients’ health conditions. First-line targeted therapy tends to involve chemotherapy as a combined treatment option. Even if the first-line treatment gradually becomes ineffective, there are still options such as combining second-line, third-line and even fourth-line treatments. Adopting immunotherapy can also be a good treatment option.

Current targeted therapy drugs appropriate for late-stage colorectal cancer are generally classified as Anti-Vascular Endothelial Growth Factor (VEGF) and Epidermal Growth Factor Receptor (EGFR). EGFR is usually used to treat patients who do not have mutations in the KRAS gene.

Frequently Asked Questions About Colorectal Cancer

As colorectal cancer symptoms may be minor or non-existent during the early stages of the disease, it is recommended to begin screening for colorectal cancer soon after turning 50 to effectively reduce your risk of developing colorectal cancer, even if you have never observed any colorectal cancer symptoms in the past. According to research conducted by the American Cancer Society, more young adults are getting colorectal cancer and therefore, people at average risk of colorectal cancer are recommended to start regular screening at age 45[9].

In addition, under the recommendations by Hong Kong’s Cancer Expert Working Group on Cancer Prevention and Screening (CEWG), Department of Health urges citizens aged 50 to take a fecal occult blood test every one to two year; or a sigmoidoscopy every five years; or a standard colonoscopy every 10 years. High-risk individuals such as those with a family history of colorectal cancer should consult a doctor and get screened at an earlier age[10].

Similar to most cancers, colorectal cancer is generally classified into 1 to 4 stages, depending on the size of the tumor, how far the cancer has spread in the body and the progression of the disease. There are individual cases to which the staging system cannot be applied. For more information, please refer to cancer staging system.

Before cancerous cells spread to other organs, surgery is usually recommended as the primary treatment for colorectal cancer. However, patients can also consider other treatment options such as combining chemotherapy with the “Watch-and-Wait” approach, immunotherapy and targeted therapy. Approximately 30% of patients with colorectal cancer who were treated with the “Watch-and-Wait” approach have found their cancerous cells disappeared completely.

In addition, for patients with stage IV colorectal cancer, treatment plan that combines chemotherapy and targeted therapy is highly regarded as suitable, because they will not only alleviate patients’ symptoms ?but also improve their quality of life. Specific treatment plan can only be determined by the nature of the tumor (such as hereditary), the age and health conditions of the patient and other health-related issues.

Patients with early-stage colorectal cancer generally are not required to undergo chemotherapy after surgery. But for patients with late-stage cancers, such as stage II and III, as it is likely that cancer cells still remain in the body after surgery, chemotherapy is highly recommended in order to lower the risk of recurrence.

Chemotherapy treatment normally lasts for three months to a year. Mainly targeted at patients with rectal cancer, radiotherapy is given five times a week for a total of six weeks. Some of the latest radiotherapy technologies such as TomoTherapy can reduce the side effects remarkably, by adjusting the size, shape and intensity of the radiation beam to accurately target the size, shape and location of the patient’s tumor and to minimize damages on surrounding tissues.

In addition, for patients with stage II and III rectal cancer, treatment plans that combine chemotherapy and radiotherapy, known as chemoradiotherapy, are recommended before the surgery. Not only can it reduce the size of the tumor and the risk of recurrence, but also reduce the likelihood of leaving a permanent stoma on the intestine of the patients after the surgery.

Before the surgery, one of the treatment options is to combine chemotherapy with the “Watch-and-Wait” approach using MRI and colonoscopy. This method can monitor the development of the disease, delay and even avoid the use of surgery. For patients who are younger or whose tumor is located closer to the anus, this combined treatment method can avoid the complete removal of the anus and sphincter and the creation of a stoma, allowing them to discharge waste as they normally would and thus greatly improving their daily life.

When the sedative wears off, movements of the intestine generally slows down. Patients are recommended to start drinking a small amount of water after two to three days of the surgery and gradually increase the amount of water intake. After four to five days, patients can start having a light diet as advised by the doctor[11].


In addition, after the removal of tumor, some patients may need to undertake a colostomy or ileostomy. They need to learn how to examine, clean and change the stoma bag. It is critically important for their family, friends and counsellors to be understanding and offer support whenever necessary during the transition.



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