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Colon Cancer - Causes, Symptoms, Diagnosis, and Treatment

Published on Sep 08, 2020   -  5 min read


Cancer arising from the inner wall of the large intestine or colon is called colon cancer. Please read the article to know about its causes, symptoms, diagnosis, and treatment options.

Colon Cancer -  Causes, Symptoms, Diagnosis, and Treatment

What Is Colon Cancer?

The type of cancer that originates in the large intestine, otherwise called the colon, is called colon cancer. The large intestine is the last part of your digestive tract. This cancer most commonly affects older adults, but it can occur at any age. Colon polyps, which are small, noncancerous clumps of cells, are usually how this cancer begins. Some of these polyps can turn cancerous over time.

As polyps are quite small and produce very few or no symptoms, it is advised to get regularly screened to prevent colon cancer. Polyps can be identified and removed before they form cancer. Various treatment options are also available for colon cancer, such as surgery, radiotherapy, and chemotherapy.

What Is Colorectal Cancer and What Are Its Stages?

The term colorectal cancer is used to describe cancer of both the colon and rectum (the end of the large intestine). Its stages are:

  1. Stage 1 - Cancer has spread to the colon or rectal mucosa, but not to the walls of the organ.

  2. Stage 2 - Cancer has spread to the walls of the colon or rectum, but not to the lymph nodes or adjacent tissues.

  3. Stage 3 - Cancer has reached the lymph nodes, but not other body parts. Generally, it involves one to three lymph nodes.

  4. Stage 4 - Cancer has spread to organs like the lungs.

What Are the Signs and Symptoms of Colon Cancer?

Most people do not experience any symptoms during the early stages of colon cancer. In case symptoms occur, they vary depending on the size of cancer and its location. The early signs and symptoms of colon cancer are:

The symptoms associated with stage 3 or 4 are:

If cancer cells spread to other parts of the body, then the symptoms might include:

When to Consult a Doctor?

Anyone who is experiencing the above symptoms persistently should book an appointment with your doctor. Get yourself screened for colon cancer. It is recommended to begin regular screening from 50 years of age. In case you have a family history of this disease, your doctor might ask you to start screening early on.

What Are the Causes of Colon Cancer?

Doctors are still trying to find the exact cause of this cancer. Even though the exact cause is not known, the following are some of the factors that increase the risk of developing colon cancer.

The best way to prevent it is by getting it surgically removed.

How Is Colon Cancer Diagnosed?

As this cancer does not produce symptoms in the early stages, doctors recommend screening tests to look for signs of colon cancer or polyps. If you are not in the high-risk group, these screening tests should be started at around 50 years, and if you are in the high-risk group, then screening should be started earlier.

The doctor will first ask you about your family history, symptoms, and medical history. He or she will then perform a physical examination by pressing on your abdomen. Then you will be asked to get the following tests done:

  1. Blood tests - To rule out other conditions that can result in similar symptoms. They will ask for liver function tests and complete blood count.

  2. Colonoscopy - Here, a long flexible tube with a camera attached to one end is inserted inside the colon through the rectum. This can help diagnose polyps and other growths.

  3. Biopsy - If needed, your doctor might remove tissue from any abnormal growth during a colonoscopy. This tissue will then be sent for laboratory testing.

  4. Double-contrast barium enema - Your bowels will be coated with a barium solution, and then X-rays are taken.

  5. CT scan - This provides a more detailed image of your colon.

What Are the Treatment Options for Colon Cancer?

Depending on the stage of cancer and your general health, the various treatment options include:

1) Surgery:

For early-stage - A minimally invasive surgery, such as -

For cancer that has grown into the colon -

Partial Colectomy - The part of the colon that contains the cancer is removed. If the doctor is not able to reconnect the healthy portions of the colon, the surgeon performs an ostomy. An opening will be created on the wall of the abdomen, through which stool is eliminated to a bag outside the body. The nearby lymph nodes are also removed.

For advanced cancer -

In advanced cases, where cancer has spread to other body parts, the doctor will perform surgeries to relieve signs and symptoms. But these surgeries will not cure cancer.

2) Chemotherapy - Medicines are used to destroy cancer cells and reduce the rate of recurrence.

3) Radiation Therapy - Powerful X-rays and protons are used to destroy cancer cells.

Both chemotherapy and radiation therapy are used to shrink cancer, which makes it easier for the surgeon to remove it. If cancer is inoperable, then these treatment options provide symptomatic relief.

The other treatment options include targeted drug therapy, immunotherapy, and palliative care.

Can Colon Cancer Be Prevented?

The following tips might help lower the risk of colon cancer:

  1. Your diet should include fruits, vegetables, and whole grains. They are a good source of vitamins and minerals.

  2. Keep your weight under check. If you are overweight, form a plan to lose weight after consulting your doctor.

  3. Avoid binge drinking and limit the consumption of alcohol.

  4. Quit smoking.

  5. Try to exercise at least four days a week for a minimum of 30 minutes.

For more information about the treatment options, consult a surgical oncologist online now.

Frequently Asked Questions


How Does One Get Colon Cancer?

Colon cancer initially begins as a polyp inside the walls of the colon and rectum. Longstanding polyps, over time, get converted to colon cancer. It is due to certain risk factors like old age, smoking, obesity, sedentary lifestyle, male sex, high intake of fats, red meat, alcohol, processed meat, low dietary fibers, pre-existing colon diseases like Crohn’s disease, ulcerative colitis, inflammatory bowel disease, and genetic diseases.


Which Age Group Does Colon Cancer Affect?

Colon cancer is known to affect the older age groups, especially those above 50 years of age. However, there is a recent trend of few cases involving people below the age of 50. Hence the colon cancer screening age has been reduced from 50 to 45 years.


What Are the Early Signs of Colon Cancer?

In the initial stages, colon cancers mostly do not cause symptoms or cause mild symptoms like thin and dark stools, abdominal bloating, and pain. But in the later stages, there will be changed or irregular bowel habits, bloody stools, persistent abdominal pain, cramps, weight loss without any effort, dissatisfied bowel emptying, constipation, and diarrhea.


Do Colon Cancer Symptoms Appear Suddenly?

Symptoms of colon cancer appear in the later stages, probably once the disease has reached the second stage. Initial benign polyps do not cause symptoms, and hence they do not come to the notice of the individual. Once they become cancerous, they cause vague symptoms like progressive weight loss, abdominal pain, cramps, darker and thinner stools which seldom gain attention.


How Can We Detect Colon Cancer?

Colon cancer screening tests help detect benign polyps and early stages of colon cancer. It includes colonoscopy and stool tests. In case of abnormal bowel habits, unidentified weight loss, abnormal stool mass, and blood in stools, immediate medical help must be sought as they may be signs of colon cancer.


How Does the Stool in Colon Cancer Look Like?

There are changes in stool’s appearance in colon cancer. The stool becomes narrower or thin, and ribbon-like. It also gets dark, black, and tar-like. Sometimes instead of a black stool, there may be blood present in the stool.


How Does Colon Cancer Pain Present Like?

Colon cancer can present with abdominal pain with cramps, and these are persistent. Also, there is a sudden urge to defecate even if the bowel is empty.


How Do I Know Whether I Have Colon Cancer or Not?

Colon cancer may not cause signs and symptoms in the initial stages. In some instances, it might not cause any symptoms until it is diagnosed accidentally. But usually causes symptoms like altered and frequent bowel movements, constipation, diarrhea, abdominal pain, bloating, cramps, thin and dark stools, weakness, fatigue, and progressive unintentional weight loss.


Is Colon Cancer More Common?

According to the American Cancer Society, it occupies the third position in the list of common cancers affecting the United States’ people. Hence it is not an uncommon condition.


How Fast Does Colon Cancer Grow and Spread?

Longstanding polyps or abnormal growths in the inner wall of the colon over time become cancerous, leading to colon cancer. Hence the transformation of a polyp to colon cancer is not a sudden one. Also, the spread and growth of colon cancer are regarded to be slow.


What Is Meant by Stage 1 Colon Cancer?

The cancerous growth is extended and limited to the deeper layers of the colon wall and may or may not include the muscle wall in stage 1 colon cancer. They do not involve the lymph nodes.


Is Colon Cancer More Dangerous?

Early detection and treatment of colon cancer give excellent life expectancy and cure rates. But treatments in the later stages of the disease after cancer has spread to distant sites and beyond the colon wall decrease the cure rate and survival rates.


Can a Blood Test Reveal Colon Cancer?

A single blood test cannot reveal colon cancer. However, a complete blood count (CBC) can show altered blood parameters like reduced hemoglobin levels correlated with the symptoms. The blood-based DNA test is a recently approved blood test to diagnose colon cancer risk in individuals above 50. It tests the presence of an altered SEPT9 gene. Colonoscopy and stool tests help in colon cancer screening.


Does Colon Cancer Spread Fast if Left Untreated?

Though colon cancer belongs to the category of slow-growing cancers, if not detected and treated early, it can invade the nearby tissues and organs and spread to distant parts of the body.


How Long Is Chemotherapy for Colon Cancer?

Based on the cancer stage and drugs, chemotherapy for colon cancer ranges from three to six months.


How to Prevent and Avoid Colon Cancer?

Excluding or limiting animal-based foods, alcohol, tobacco, and including a high fiber diet including fruits, vegetables, and whole grains help prevent colon cancer. Actively involving in regular physical activity also reduces the risk.

Article Resources

Last reviewed at:
08 Sep 2020  -  5 min read




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