Colon Cancer – Types, Causes, Diagnosis, Treatment

Colon, commonly known as large intestine is the last part of our digestive tract. Most of the times, it is possible to determine colon cancer at an early stage. It is because the colon cancer is noncancerous in nature and develops into clumps of cells known as adenomatous polyps. Over time, these polyps can develop into dangerous lumps and become colon cancer.

Such polyps might be small and few. But when there is a tumorous growth of the cells, then this results in colon cancer. It is the third most common form of cancer worldwide, but the good thing is that identifying colon cancer at an early stage can help treat it and lead to steady improvements in survival.

Before we read about the causes and treatment of colon cancer, first let’s know about the types of colon cancer.

Types of Colon Cancer

  1. Adenocarcinomas – It is the most common type of colon cancer. This cancer begins in cells that make mucus to lubricate the inside of the rectum and colon. Some forms of adenocarcinomas cancers can get worse and form sub-types, like mucinous and signet ring.
  2. Carcinoid tumours – This form of colon cancer starts from special hormone-making cells within the intestine. They are present in gastrointestinal carcinoid tumours.
  3. Lymphomas – It is a cancer of immune system cells. They mostly begin in lymph nodes but can also spread into the rectum, colon, or other body organs.
  4. Gastrointestinal Stromal Tumors or GISTs – This cancer starts from special cells in the wall of the colon. They are also called the interstitial cells of Cajal. Some of such cancer is benign in nature. These tumours can be identified in any part of the digestive tract. But it is not common in the colon.
  5. Sarcomas – This form of cancer can begin in blood vessels, muscle layers, as well as other connective tissues in the wall of rectum and colon. Sarcomas cancer is rare.

Causes of Colon Cancer

In most of the cases, the cause of colon cancer is not known. But as per most of the studies, it occurs when healthy cells in the colon develop issues in the genetic DNA.

Healthy cells grow and divide rapidly in an orderly manner to keep your body functioning normally. But when the DNA of cells damage it becomes cancerous and these cells continue to divide even when new cells are not required. Once these cells accumulate, they develop into a tumour.

With time, these cancer cells can grow to expand and destroy normal or healthy tissues in the body. If left untreated, then these cancerous cells can travel into other parts of the body to create deposits, known as metastasis.

In addition to issues in DNA, the other causes of colon cancer are:

  • Inherited Gene Mutations – This increases the risk of colon cancer, which can be passed through families. But such inherited genes are found only in the small percentage of colon cancers.
  • Older Age – A large majority of individuals diagnosed with colon cancer are more than 50 years. Colon cancer can occur in young individuals too, but the chances are very rare.
  • A history of polyps or colorectal cancer – If you have a history of colon cancer or adenomatous polyps, you are at a greater risk of colon cancer.
  • Inflammatory Conditions of the Intestine – Chronic inflammatory illnesses of the colon, like Chron’s disease or ulcerative colitis can result in colon cancer.
  • Family History of Colon Cancer – You are likely to develop colon cancer if you have a sibling, parent, or child suffering from the disease. If anyone of your family member has rectal or colon cancer, then you are at a higher risk.
  • High-fat or Low-Fiber Diet – Rectal cancer and colon cancer can be associated with a diet high in fat and low in fibre. Some studies have determined an increased risk of colon cancer in individuals who consume diets high in processed meat or red meat.
  • Diabetes – Individuals suffering from diabetes are at a higher risk of experiencing colon cancer.
  • Living a sedentary lifestyle – If you live an inactive or sedentary lifestyle, you are more likely to develop colon cancer.
  • Smoking – Individuals who smoke have an increased risk of colon cancer.
  • Obesity – Individuals who are obese have a high risk of colon cancer and even dying with the same.
  • Alcohol – Heavy intake of alcohol increases the risk of colon cancer.
  • Radiation therapy for cancer treatment – If you had a history of cancer of abdomen, then radiation therapy used to treat it can increase the risk of rectal and colon cancer.

Diagnosis of Colon Cancer

The diagnosis process of colon cancer begins with its screening.

Doctors suggest certain screening tests for people with mild or no symptoms of colon cancer in order to determine it at an early stage. Finding colon cancer at an early phase provides the highest chance for cure. Early screening can even help reduce risks associated with colon cancer.

People can have a screening for colon cancer at the age of 50. But those with family history must consider an early screening.

There are different options available for screening of colon cancer, each having its own drawbacks and benefits. You can decide an appropriate screening process for yourself after having a detailed discussion with your doctor. If colonoscopy is used to screen colon cancer, it is possible to remove polyps before they become cancerous.

If you disclose certain symptoms of colon cancer, your doctor would suggest one or more procedures and tests, such as:

  • Blood Test

Though a blood test alone cannot confirm the existence of colon cancer, your doctor may test your blood to determine your overall health condition, like live and kidney functioning.

A blood test is also performed in order to determine the presence of any chemical released by colon cancer. This is done by testing the CEA level in blood. The level of CEA also helps the doctor to know about your prognosis and how your body is responding to the treatment.

  • Using a Scope to Analyze the Inside of Your Colon

This process is known as colonoscopy, which uses a flexible, long and slender tube connected to a video camera and a monitor to view your entire rectum and colon. If any suspicious aspects are identified, your doctor can use surgical tools through the tube to take a tissue sample for the process of biopsy and remove polyps.

Treatment of Colon Cancer

Based on your diagnosis, your doctor would stage the colon cancer at various levels or stages. The type of treatment is then offered based on the stage of your colon cancer. Primarily, colon cancer is cured with treatment options like chemotherapy, surgery, and radiation. (read more)

Surgical Treatment for Early-Stage Colon Cancer

The colon cancer at an early stage is very small. Hence, your doctor would suggest you minimally invasive surgery, like:

  • Eliminating Polyps through Colonoscopy – If cancer is small, localized and totally contained in a polyp and is at a very early stage, then colon cancer can be removed completely during a colonoscopy.
  • Endoscopic Mucosal Resection – It is possible that removing bigger polyps would need to take a small amount of the lining of the rectum or colon in a process known as endoscopic mucosal resection.
  • Minimally Invasive Surgical process – If it is not possible to remove polyps through colonoscopy then a laparoscopic surgery is performed to remove them. During this process, a surgeon makes multiple small incisions in the abdominal wall and inserts instruments connected to cameras that display the colon on a video monitor. Additionally, your surgeon might also take a sample from lymph nodes in the region where cancer is located.

Surgical Process for Invasive or Severe Colon Cancer

The above surgical processes would not be able to rectify your colon cancer if it has grown through or into your colon. In this case, your doctor would suggest you severe colon cancer surgery.

  • Partial Colectomy – This surgical process involves removal of the part of colon affected with cancer along with a margin of typical tissue on sides of cancer. After the removal process, your surgeon reconnects the healthy portions of the rectum or colon. This process is usually done by laparoscopy or minimally invasive surgery.
  • Surgery to create an artificial way for waste to leave your body – When it is not feasible to reconnect the healthy parts of your rectum or colon, then you would need an ostomy. It is a process that involves creating an artificial opening in the abdomen’s wall from a part of the remaining bowel for the elimination of stool into a bag that is securely fitted over the opening. In most of the cases, this process is temporary.
  • Removal of Lymph Node – It is also essential to remove nearby lymph nodes during surgery of colon cancer.

Surgical Process for Advanced Colon Cancer

If your colon cancer is a very advanced stage or has affected your overall health condition, then surgery is performed to relieve a blockage of the colon and in order to improve your symptoms. This surgical process is not done to cure cancer, but alleviate the symptoms like pain and bleeding.

If your overall health condition is good, your doctor would then suggest you remove cancerous lesions from the liver. Usually, chemotherapy is performed before this surgical process.


The process of chemotherapy uses drugs to destroy cells that have become cancerous. Chemotherapy is mainly offered after surgery is cancer had spread to the lymph nodes. This way, chemotherapy helps to reduce the risk of recurrence of cancer.

In some cases, chemotherapy may also be used before surgery. This process is more common in rectal cancer than colon cancer.

The process of chemotherapy can also help to relieve colon cancer symptoms that have spread to other parts of the body.

Radiation Therapy

This is another process that utilizes powerful energy sources, such as X-rays to kill cancer cells and to shrink big tumours before surgery is considered so that it is possible to remove them easily.

Radiation therapy is offered alone or combined with chemotherapy is a standard treatment option for the management of colon cancer at an initial stage.


Some patients suffering from advanced colon cancer can get benefit from immunotherapy involving antibodies like pembrolizumab and nivolumab. Colon cancer can respond well to these immunotherapies, which is determined by a particular test of tumour tissue.

Drug Therapy

There are some special drugs that target particular malfunctions that enable cancer cells to grow. Some of these drugs are:

  • Cetuximab
  • Bevacizumab
  • Regorafenib
  • Ramucirumab
  • Panitumumab
  • Ziv-aflibercept

Such drugs are offered along with chemotherapy and are usually offered to people with advanced cancer.

Palliative or Supportive Care

This is a specialized form of medical care that focuses on offering relief from pain and other signs of severe illness. This treatment is offered by palliative care specialists who offer additional care support to complement the ongoing care.

Proper use of palliative care along with other treatments can help people suffering from colon cancer to feel better and live longer.

Just like other types of cancers, even colon cancer is risky and life-threatening. However, the good thing is that an early diagnosis can help alleviate it and make you live a healthy life. Hence, if you suspect the presence of colon cancer symptoms, then it is wise to visit a doctor at the earliest.

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