Definition & Overview

Cancer occurs when abnormal cells continue to grow and begin attacking other cells, causing major damage to organs and tissues. Cancer is named according to the part of the body where it originates. Therefore, colorectal cancer is cancer that originates in the colon and rectum.

Colorectal cancer is one of the most prevalent types of cancer in the world. Millions of new cases are reported every year. However, due to improvements in the early detection of the disease, treatment methods, and information dissemination on cancer prevention, fatalities have significantly decreased.

Around 95% of colorectal cancers are adenocarcinomas, which is a type of cancer that originates from glandular structures. The remaining 5% are adenosquamous and mucinous carcinomas.

Colorectal cancers typically begin as polyps on the inner walls of the rectum or colon. Not all polyps become cancer, but some may continue to grow and eventually become cancerous. The key to preventing them from becoming cancer is to locate and remove them as early as possible. However, this is not an easy task as polyps, particularly small ones, are very difficult to detect. They may also not produce any symptoms, which is why many people don’t even know that they’re at risk of developing colorectal cancer.

Fortunately, advances in screening technologies have allowed doctors to identify polyps that have a greater chance of developing into cancer.

Cause of Condition

To this date, the exact reason why colon cancer cells develop is not clear. However, researchers have identified several factors that increase the risk of its development. These include:

  • Heredity – certain gene mutations linked to colon cancer can be inherited. The presence of these genes does not necessarily mean a person will develop colon cancer, but when compared to the rest of the population, they have a higher risk of developing the disease. Therefore, those who have immediate family members or relatives with the disease should exercise the necessary precautions.

  • Lifestyle – Studies have shown that an unhealthy lifestyle (smoking, excessive alcohol consumption, obesity, an unhealthy diet, and a sedentary lifestyle) also increases the risks of colon cancer.

  • Diabetes – Type 2 diabetes is known to result in a variety of conditions, such as heart problems, stroke, and colon cancer.

  • Radiation therapy – undergoing radiation therapy to treat other forms of cancer can also increase the risk of developing colon cancer.

  • Age – Anybody of any age can be affected by colon cancer, but statistics shows that those above the age of 50 are at a higher risk.

Key Symptoms

The symptoms of colorectal cancer may or may not be present during the early stages. However, as the disease progresses, patients are bound to experience one or more of the following:

  • Bloody stool
  • Abdominal pains
  • General weakness
  • Fatigue
  • Weight loss with no apparent cause
  • Constipation
  • Episodes of diarrhea

It’s important to understand that colorectal cancer is one of the most preventable forms of cancers due to available advanced screening methods. If you are concerned about the possibility of developing the disease because of known risk factors, it would be best to undergo annual cancer screening, especially if you’re above 50.

Who to See and Types of Treatment Available

The above symptoms are not exclusive to colon cancer. As such, patients who experience them are not automatically given a diagnosis. Several tests, such as a blood test and fecalysis, will be ordered to rule out the presence of other conditions. If initial tests suggest the possibility of colon cancer, the patient will be referred to an oncologist who will then order additional tests including a colonoscopy, which involves inserting a small tube into the colon to look for any obvious signs of cancer. For patients who do not qualify for this diagnostic test, CT colonography, which uses CT-scan to create a detailed image of the colon, will be performed.

If the tests confirm colorectal cancer, the oncologist will proceed by determining the extent of the damage, which will be taken into consideration when choosing the most appropriate treatment method. The stages of colon cancer are the following:

  • Stage 1 - cancer has not spread beyond the colon or rectum
  • Stage 2 - cancer has penetrated the wall of the rectum or colon, but has not affected other lymph nodes
  • Stage 3 - cancer has spread to the nearby lymph nodes but has not affected other body parts
  • Stage 4 - cancer has spread to other organs, such as the lungs or liver

The primary method of treatment for early stages is the surgical removal of cancer polyps, usually during a colonoscopy or an endoscopic mucosal resection. Both methods are highly efficient and usually no other forms of treatment will be required.

Meanwhile, patients with advanced colorectal cancer will undergo various treatment methods, which include surgery to remove the cancer cells from the affected organs, chemotherapy, radiation therapy, and drug therapy. If the condition has already resulted in a blockage in the colon, the doctor will surgically remove the blockage to alleviate the symptoms.


  • Burt RW, Barthel JS, Dunn KB, et al. NCCN clinical practice guidelines in oncology. Colorectal cancer screening. J Natl Compr Canc Netw. 2010 Jan;8(1):8-61.

  • Engstrom PF, Arnoletti JP, Benson AB 3rd, et al. NCCN Clinical Practice Guidelines in Oncology: colon cancer. J Natl Compr Canc Netw. 2009 Sep;7(8):778-831.

  • Itzkowitz SH, Potack J. Colonic polyps and polyposis syndromes. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger & Fordtran’s Gastrointestinal and Liver Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 126.

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