Colorectal cancer is a cancer of the tissues of the large intestine and colon. A common type of colorectal cancer is caused by abnormal proliferation and growth of the epithelial lining of the intestine that becomes a small lump, called a polyp. Over time some of these polyps may turn into cancer. The resection of polyps can prevent from becoming cancerous. Untreated colorectal cancer can spread through the intestinal wall or metastasise to the liver, lungs, peritoneal lining, brain or bone.
The following group of symptoms indicate colorectal cancer:
Changes in the bowel habits of an individual, increased frequency or worsening of constipation, incomplete bowel emptying or trouble having a bowel movement (straining to go)
Diarrhoea alternating with constipation.
Fresh or dark red bloody stool.
Changes in stool characteristics, i.e. stool lumps changed to thin and flat form.
Bloating, abdominal pain, dyspepsia, gas in bowel (abdominal discomfort).
Unexplained weight loss.
Tired, fatigue, unable to do usual routines.
>> If you notice these symptoms, see your doctor immediately for further investigation for the cause of the symptoms.
In the early stage of cancer. The cancerous tissue is found only in the inner lining of the colon or rectum, and limit within the polyp.
Treatment: Surgical removal of the cancerous part of the intestine. Any other surgery will not be performed, unless the resection cannot completely remove the polyps.
Tumors have grown more than stage 0 and embedded in the muscle layers of the large intestine and colon without spreading into surrounding tissues or lymph nodes, and stay within muscle layers of the large intestine.
Treatment: Surgical removal of the cancerous part of the intestine.
Tumors have spread out into the lining of the large intestine and outer part of the anus or surrounding tissues, but do not spread into lymph node.
Treatment: Surgical removal of the cancerous part of the intestine. Some of the cases may also need chemotherapy after surgery. For sigmoid colorectal cancer, chemotherapy in combination with radiation are given before or after surgery.
Cancer has spread out of the intestine and into lymph nodes surrounding the large intestine, but does not spread into other organs.
Treatment: Surgical removal of the cancerous part of the intestine followed by chemotherapy. For sigmoid colorectal cancer, chemotherapy in combination with radiation are given before or after surgery.
Cancer has spread into other organs, usually the liver and lung.
Treatment: Chemotherapy. Consider using targeted therapy for treatment efficacy. Some cases may also need a surgery.
Screening test for colorectal cancer is the test in general people whose symptoms are not suspected of cancer. The objectives are to detect cancer in early stage and to decrease cancer mortality rate since screening. Screening test for colorectal cancer can be done by various methods as follows:
Stool examination to find hidden red blood cells or to find small amount of blood contaminated in stool (occult blood) which is not visible
tumor in the large intestine will be come off, allowing us to detect abnormal DNA in faeces.
(Computed tomographic (CT) Colonography) is the new modern testing technique by inflation of gas into the large intestine, which enlarges its size and enables us to see as much as possible, then make x-ray image in a horizontal plan. After that, data obtained is then further processed togenerate a virtual 3D picture of the inside of the large intestinal to look at the abnormalities. For example,
polyp, other lesions present in the large intestine, etc.
Insertion of a camera through the anus to investigate abnormalities of the rectum and flexible colon. If lesion is found, this procedure can then remove the tissue for further examination.
Insertion of a camera through the anus to get the images inside of colon and rectum areas. We can remove the suspected tissues for pathological investigation and it is the most precise procedure.
The main objective is to remove the tumors out of the body.
Surgeon will surgically remove the cancerous parts of the intestine along with its surrounding lymph nodes, then he/she will connect the remaining parts of the intestine to one another. If this option cannot be done, parts of large intestine will be brought through an opening made in the abdominal wall for stool to drain either temporarily or permanently.
However, this depends on patient’s condition and how advanced the tumors are spread out. Opening of the abdominal wall for the large intestine is the change of gastrointestinal direction for defecation
Opening of the abdominal wall for the large intestine is called Colostomy.
The high dose of radiation to eliminate the cancer cells.
The radiation therapy is typically used in the sigmoid colorectal cancer
Before the surgery To reduce the tumor size that allows easier surgery.
After the surgery To destroy the remaining cancer cells and to decrease the rate of recurrence.
Chemotherapy in combination with radiation are preferred for better treatment.
In patients with very large tumors or metastatic lymph nodes, they usually receive chemotherapy after the surgery that is called adjuvant treatment after the surgery to remove the remaining cancer cells. This is the treatment to decrease the chance of recurrence and to increase patient survival rate or called curative treatment.
Chemotherapy is also used as the primary treatment in patients with metastatic or inoperable colorectal cancer. Chemotherapy is then used to stop cancer from metastasis, to alleviate symptoms or suffering from cancer and for the best quality of life. Also, it is to increase the patient’s survival rate which is called supportive treatment.
There are 2 administration methods of chemotherapy as follows:
Intravenous chemotherapy is currently the standard chemotherapy. The combination of one or more drugs are usually used in the chemotherapy for the best efficacy. Treatment will be done in cycles. Each cycle has an interval as well as resting period. the number of interval and resting period are based on chemotherapy regimen. Doctor will determine which is considered most appropriate regimen for each individual patient.
The treatment efficacy is not different from that of intravenous chemotherapy. It has been developed to enhance treatment compliance for patient, caregiver, and family and to help them continue normal activities. Since intravenous chemotherapy can be painful in certain patients and time-consuming for caregivers and family who accompany the patients to the hospital.
It is the new treatment to inhibit cancer directly at the target, for example, antiangiogenesis therapy, and anti-epidermal growth factor receptor, etc.
These drug groups are often used in combination with chemotherapy for greater treatment efficacy. They can prolong survival and disease-free period, and increase the tumor response rate better than chemotherapy alone. The doctor will advise which drug is suitable for each patient. It is important to know that even if you have the same type of cancer as someone else, your DNA mutations may differ, and you may need different treatment. By taking a look into your cancer DNA mutations with Comprehensive Genomic Profiling, your doctor can consider this information for identifying the most appropriate treatment approach for your cancer.6-8
Common side-effects from targeted therapy are as follows:
Anti-angiogenesis therapy, e.g. high blood pressure, thrombosis easy bleeding, detached wound, gastrointestinal perforation, proteinuria,etc.
Anti-epidermal growth factor receptor, e.g. diarrhea, rash, dry skin, peeling skin, sun-sensitive skin,etc.
Treating doctor will follow up patients after treatment to provide continuous care. In general, patients will see doctor 3-6 months after surgery in the first 2 years and every 6 months up to 5 years for follow up. Physical examination, blood test for tumor marker, and other tests, e.g. colonoscopy and radiodiagnosis, will be performed in the follow up, and doctor will determine the timing as appropriate.
National Cancer Institute by NIH. Colorectal Cancer for Patient. Available at:
The National Comprehensive Cancer Network, Inc. NCCN Guidelines for Patients® Colon Cancer Version 1.2017. Available at:
The National Comprehensive Cancer Network, Inc. NCCN Guidelines for Colorectal Cancer Screening Version 1.2018. Available at:
American Cancer Society. About Colorectal Cancer. Available at:
Cancer Research UK. Bowel Cancer. Available at:
Heim D et al. Int J Cancer 2014; 135: 2362–2369
Baumgart M et al. Am J Hematol Oncol 2015: 11: 10–13
Schwaederle M, Kurzrock R. Oncoscience 2015; 2: 779–780.
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