Colon Cancer: Symptoms, Causes, Diagnosis & Treatment

Colon cancer is a type of cancer that begins in the intestine and typically affects older adults but can occur at any age. Colon cancer originates when healthy cells in the colon develop mutations in their DNA, leading to the uncontrollable growth of abnormal cells. 

The colon is the last part of the digestive tract and assists in processing food for energy and eliminating waste from the body. The colon wall comprises layers of mucous membrane, tissue, and muscle.

Diagnosing colon cancer involves a variety of tests, including blood tests, imaging studies, and a colonoscopy. The stage of the cancer is then identified, which impacts the treatment options and prognosis.

Treatment options for colon cancer may include surgery, chemotherapy, radiation therapy, or targeted therapy. Lifestyle changes and early screening can help in prevention while ongoing research continues to explore new ways to prevent and treat this disease. 

Early detection and treatment of polyps can significantly reduce the risk of developing colon cancer.


Early detection through screening tests can enhance prognosis and provide greater chances of successful treatment. Symptoms for colon cancer vary and can sometimes be hard to pinpoint. 

However, it’s essential to be aware of these signs to seek medical help early for a higher chance of successful treatment. Some of the common symptoms are:

Changes in Bowel Habits 

Persistent changes in your bowel movements can be a sign of colon cancer. 

This can include diarrhea, constipation, or a change in the consistency of the stool.

Blood in the Stool or Rectum 

The presence of bright red or dark blood in your stool is a key symptom.

This often indicates an issue in the colon or rectum.

Abdominal Pain and Cramps 

Experiencing persistent pain, discomfort, or cramps in the abdominal area can be a sign of colon cancer.

These discomforts are often dismissed as routine digestive issues. However, persistent or increasing pain warrants medical attention to rule out other conditions.

Weight Loss 

Unexplained and sudden weight loss can be a symptom of colon cancer. 

If you are not on a weight loss program and still experience this issue, it’s important to consult a doctor.

Fatigue and Weakness 

Constant fatigue and feeling weak without apparent reason might also indicate colon cancer.

These are non-specific symptoms that can also present with anemia or malabsorption but can occur in individuals with colon cancer.

Bloating and Gas

Although these symptoms are quite common and can be caused by various factors, persistent bloating and gas that doesn’t seem to improve might be a sign of colon cancer.

If you notice prolonged or severe bloating and gas, consult a healthcare provider for further evaluation.


Though less common, vomiting can be a symptom of colon cancer, especially when accompanied by other symptoms stated above.

Remember that these symptoms are not specific to colon cancer and can be caused by other health issues. Nevertheless, if you experience any of these signs, especially multiple ones, or a symptom persists over time, consult your doctor for proper diagnosis and treatment.

Causes and Risk Factors

Understanding the causes and risk factors of colon cancer is crucial for effective prevention and early diagnosis. While the exact cause remains unclear, several factors can elevate the risk.

Polyp Growth

One major cause is the presence of polyps in the colon or rectum. Polyps are abnormal growths that can develop into cancer if left untreated. Some common types of polyps include adenomatous polyps and inflammatory polyps.

Colon cancer starts in the mucosa, the innermost lining of the colon, which consists of cells that make and release mucus and other fluids. If these cells mutate or change, they have the potential to develop a colon polyp.


Age is another significant risk factor for colon cancer. 

While it can occur at any age, the risk increases as people get older, with most cases diagnosed in individuals over 50.


Gender also plays a role, as studies have shown that men are more likely to develop colon cancer than women.

This difference has been attributed to varying lifestyle factors and hormonal profiles between genders.


Lifestyle factors can also contribute to the risk of developing colon cancer. 


Tobacco use has been linked to an increased risk of colon cancer, as well as many other cancers.

Alcohol consumption 

Excessive alcohol consumption can increase the risk of colon cancer.


A diet high in red and processed meat has been shown to increase colon cancer risk, while a diet rich in fruits, vegetables, and whole grains may help reduce the risk.

Medical Conditions

Having certain medical conditions increases the risk of colon cancer. 

These include illnesses such as inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis, and Lynch syndrome, a hereditary condition that increases the risk.

Additionally, people with diabetes, a history of colon polyps, or previous colon cancer are at an increased risk.

Family History and Ethnicity

A family history of colon cancer can also elevate the risk, especially if a close relative was diagnosed before the age of 60 or if multiple relatives have been diagnosed.

Ethnicity has been found to be a factor as well. Studies show that black individuals have a higher risk of colon cancer.


Colon cancer diagnosis typically involves physical examination by a doctor, blood tests, colonoscopy, and imaging studies such as CT scans or MRIs. Early detection and intervention play a crucial role in the successful treatment of colon cancer. 

History Taking and Assessment

Diagnosing colon cancer often begins with taking a thorough medical history and performing a physical exam. 

During the examination, the doctor will look for any abnormalities or symptoms that might suggest colon cancer.


Screening plays a crucial role in early detection and prevention of colon cancer. Doctors recommend regular colon cancer screening for healthy individuals with no signs or symptoms. This can involve testing for blood in the stool, colonoscopy, or other imaging techniques.

For those with a family history of colon cancer or suspected Lynch syndrome, a hereditary condition that increases the risk of colon cancer, more frequent screenings may be necessary.

Specimen Tests

One of the first tests that may be performed is a fecal occult blood test (FOBT) or a fecal immunochemical test (FIT). 

These tests check for the presence of blood in the stool, which can be a sign of colon cancer or other gastrointestinal issues.

Colonoscopy and Sigmoidoscopy

If these tests come back positive or if there is a strong suspicion of colon cancer, the doctor will likely order a colonoscopy or sigmoidoscopy. 

A colonoscopy is a procedure where a small camera is inserted into the colon to examine its lining and detect any polyps or tumors. If polyps are found, they can be removed during the colonoscopy to prevent them from turning into cancer.

A sigmoidoscopy is a similar procedure but examines only the lower portion of the colon. This test is less invasive and generally faster than a colonoscopy, but it may not detect cancerous growths in the upper part of the colon.


If cancer is suspected or confirmed, a sample may be taken during colonoscopy or sigmoidoscopy to analyze the cells under a microscope and determine whether they are cancerous. 

In some cases, the biopsy sample will also be tested for specific DNA mutations that could provide additional information about the type and stage of the cancer.

Imaging Tests

Imaging tests such as an ultrasound or MRI might be used to get a clearer picture of the colon and surrounding tissues, mainly if there is suspicion of cancer spreading to other organs.

These images can reveal tumors, obstructions, and other signs of colon cancer.

Blood Tests

A complete blood count (CBC) may also be ordered to check for anemia or other abnormalities that could be related to colon cancer.

Early detection is crucial in increasing the chances of successful treatment and improving the patient’s prognosis.

Cancer Staging

Cancer staging is an essential process in determining the extent of colon cancer and formulating appropriate treatment plans. 

Stage 1 and 2 colon cancer are typically confined to the colon wall.

Stage 3 colon cancer has spread to nearby lymph nodes. 

In Stage 4 colon cancer, the cancer has disseminated to distant organs, such as the liver or lungs.

Prognosis and Survival Rate

The outlook for patients with colon cancer is largely dependent on the cancer stage at diagnosis. 

US statistics show the relative survival rate five (5) years after colon cancer is detected based on the localization as around 91% if the tumor is localized, approximately 72% if spread regionally, around 13% if the cancer has metastasized to distant parts of the body, with a combined average of around 63% who survive for five (5) years post-diagnosis compared to the overall population.

Treatment and Management

Treatment options vary depending on the stage of colon cancer and individual patient factors. Common interventions include surgery, chemotherapy, radiation therapy, and immunotherapy. 

The choice of therapy is often influenced by the cancer stage, tumor characteristics, and overall patient health. In most cases, a combination of therapies may be used to manage and treat the cancer effectively.

Primary Approach

The primary treatment for early-stage colon cancer is surgery, which involves removing the tumor and nearby lymph nodes. 

For more advanced cases, surgery can be combined with other treatments, such as chemotherapy and radiation therapy.

Targeted Therapy

Certain types of colon cancer might require targeted therapy. This treatment focuses on specific abnormalities within cancer cells that allow them to grow, helping to stop or slow their growth. 

These therapies can be administered alone or in conjunction with chemotherapy or radiation therapy.

Advanced Stage

Liver involvement is a common occurrence in advanced colon cancer. 

If the cancer has spread to the liver, treatment options may include surgery, chemotherapy, targeted therapy, or other methods such as ablation (the destruction of cancerous cells using heat, cold, or other techniques).

Lifestyle Changes

Patients with colon cancer are often advised to make lifestyle changes, such as adopting healthier bowel habits. 

This can include increasing fiber intake, staying hydrated, and exercising regularly to promote digestive health. It’s essential to understand that staging plays a significant role in determining treatment. 

Accurate staging allows doctors to determine the extent of the cancer in the body and choose appropriate therapies.


Preventing colon cancer primarily revolves around maintaining a healthy diet and lifestyle, along with regular screenings and early detection. 

Colon Polyp Removal

In some cases, cancerous adenomas (polyps) are detected during the screening process. These are non-cancerous growths that can develop into colon cancer if left untreated. Removing adenomas can help prevent future cancer development.

It is essential to have regular screenings to detect and remove colon polyps before they develop into cancer. Depending on your age and risk factors, your healthcare provider may recommend specific screening tests, such as colonoscopies, for effective prevention and early detection.

Healthy Diet

A diet abundant in fruits, vegetables, and whole grains can assist in reducing the risk of developing colon cancer. 

These foods contain vitamins, minerals, and antioxidants that support the digestive tract and keep the mucosa lining healthy, thus preventing the formation of potential carcinogenic agents.

Physical Activity

Physical activity is another crucial aspect of colon cancer prevention. Regular exercise not only helps in maintaining a healthy body weight but also reduces risks associated with colon cancer.

Aim to incorporate at least 30 minutes of moderate physical activity into your daily routine. This can include activities such as walking, jogging, swimming, or cycling.

Smoking and Drinking Alcohol

In addition to diet and physical activity, it is important to avoid tobacco use and limit alcohol consumption. 

Tobacco products contain carcinogenic substances that can increase the risk of colon cancer, while excessive alcohol intake can damage blood vessels and lead to digestive tract issues.

Strive to quit smoking and consume alcohol in moderation to reduce your risk of developing colon cancer.

Regular Screening and Checkups

Regular screenings and early detection of colon polyps also play a vital role in reducing the chances of developing this disease. 

By focusing on these preventative measures, you can significantly lower your risks of colon cancer.

Frequently Asked Questions

What are the early warning signs of colon cancer?

Some early warning signs of colon cancer include a change in bowel habits, blood in or on your stool, diarrhea, and constipation.

Other signs include a feeling that the bowel does not empty all the way, abdominal pain or cramps that do not go away, and unexplained weight loss.

How does colon cancer get diagnosed?

Colon cancer can be diagnosed through various methods, such as colonoscopy, sigmoidoscopy, fecal immunochemical test (FIT), and fecal occult blood test (FOBT). 

Your doctor will determine the appropriate test based on your symptoms and medical history.

What are the main causes of colon cancer?

Colon cancer mainly occurs when abnormal cells grow out of control in the large intestine (colon). 

Genetic mutations, family history of colon cancer, a diet high in red and processed meats, obesity, smoking, alcohol consumption, and a sedentary lifestyle can all increase the risk of developing colon cancer.

How can colon cancer be prevented?

To help prevent colon cancer, maintain a healthy lifestyle by staying active, eating a balanced diet rich in fruits, vegetables, and whole grains, maintaining an ideal body weight, quitting smoking, and limiting alcohol consumption. 

Additionally, scheduling regular colon cancer screenings, such as colonoscopies or sigmoidoscopies, is crucial for early detection and prevention.

What are the different stages of colon cancer?

Colon cancer has four main stages, ranging from stage I (the earliest stage) to stage IV (the most advanced stage). In stage I, the cancer is confined to the inner lining of the colon, while in stage IV, the cancer has spread to other distant organs. 

The prognosis and treatment alternatives depend on the stage of cancer at the time of diagnosis.

What are the treatment options for colon cancer?

Treatment options for colon cancer vary depending on the stage and location of the cancer. They may include one or a combination of surgery for tumor removal, chemotherapy, radiation therapy, targeted therapy, and immunotherapy. 

Your doctor will decide on the best course of treatment based on your specific situation and preferences.