Colon Cancer

Colon cancer is one of the most common types of cancer worldwide but also can be highly preventable and treatable. Discover the possible risk factors and causes along with diagnosis and treatment of the disease.

What is Colon Cancer?

Colon cancer, also known as colorectal cancer, is a malignant tumour that develops in the colon or rectum, which are parts of the large intestine.

Colon cancer typically arises from precancerous growths called polyps that form on the inner lining of the colon or rectum. Over time, some polyps may develop into cancerous tumours if left untreated.

Colon cancer is one of the most common types of cancer worldwide, but it is also highly preventable and treatable when detected early.

Causes

The exact cause of colon cancer is not fully understood, but it is believed to involve a combination of genetic, environmental, lifestyle, and dietary factors. Possible risk factors and causes include:

• Age: Advancing age is a significant risk factor for colon cancer, with the majority of cases occurring in individuals over the age of 50. Colon cancer is rare in younger adults but becomes more common with increasing age.
• Family History: A family history of colon cancer or polyps, particularly in first-degree relatives such as parents, siblings, or children, increases the risk of developing the disease. Certain genetic mutations or inherited syndromes, such as familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary nonpolyposis colorectal cancer), may predispose individuals to colon cancer.
• Personal History of Polyps or Cancer: Individuals who have a history of precancerous polyps, colorectal cancer, or inflammatory bowel disease (such as Crohn’s disease or ulcerative colitis) are at increased risk of developing colon cancer.
• Dietary Factors: Diet may play a role in colon cancer risk, with high consumption of red meat, processed meats, fried foods, and foods high in saturated fats being associated with an increased risk. Conversely, diets rich in fruits, vegetables, whole grains, fibre, and antioxidants may help reduce the risk of colon cancer.
• Obesity: Excess body weight, particularly abdominal obesity, has been linked to an increased risk of colon cancer. Obesity is associated with chronic inflammation, insulin resistance, altered hormone levels, and changes in gut microbiota, which may promote cancer development.
• Physical Inactivity: Lack of regular physical activity or sedentary behaviour is a risk factor for colon cancer. Exercise helps maintain a healthy weight, promotes bowel regularity, reduces inflammation, and may lower colon cancer risk.
• Smoking: Cigarette smoking is a known risk factor for colon cancer and is associated with an increased risk of developing polyps and colorectal cancer. Smoking exposes the body to carcinogens and harmful chemicals that can damage DNA and promote cancerous changes in the colon.
• Alcohol Consumption: Excessive alcohol consumption, particularly heavy or chronic alcohol use, is associated with an increased risk of colon cancer. Alcohol may promote carcinogenesis through various mechanisms, including direct toxic effects, impaired DNA repair, and disruption of gut microbiota.
• Chronic Inflammation: Chronic inflammation of the colon or rectum, such as in inflammatory bowel diseases (IBD) like Crohn’s disease or ulcerative colitis, increases the risk of developing colon cancer over time. Prolonged inflammation can lead to tissue damage, genetic mutations, and dysplastic changes that predispose to cancer.

Symptoms

Colon cancer may not cause symptoms in its early stages, and symptoms may vary depending on the size, location, and extent of the tumour. Common symptoms of colon cancer may include:

• Changes in Bowel Habits: Persistent changes in bowel habits, such as diarrhoea, constipation, or changes in stool consistency (e.g., narrow or pencil-thin stools), may occur with colon cancer.
• Rectal Bleeding: Bleeding from the rectum, which may present as bright red blood in the stool, on toilet paper, or in the toilet bowl. Rectal bleeding may be intermittent and may vary in severity.
• Abdominal Pain or Cramping: Persistent abdominal pain, cramping, discomfort, or bloating may occur with colon cancer, especially if the tumour obstructs the bowel or causes inflammation.
• Unexplained Weight Loss: Unintended weight loss, fatigue, weakness, or malaise may occur with advanced colon cancer, particularly if the tumour affects nutrient absorption or metabolism.
• Anaemia: Chronic blood loss from the gastrointestinal tract, such as from bleeding polyps or tumours, may lead to iron deficiency anaemia, resulting in symptoms such as fatigue, weakness, pallor, or shortness of breath.
• Incomplete Evacuation: Sensation of incomplete evacuation or tenesmus (a feeling of needing to pass stool even after bowel movements) may occur with obstructive tumours or rectal involvement.
• Obstruction: Advanced colon cancer may cause partial or complete obstruction of the bowel, leading to symptoms such as severe abdominal pain, distention, nausea, vomiting, constipation, or inability to pass gas.

Diagnosis and Evaluation

If you experience symptoms suggestive of colon cancer or if you have risk factors for the disease, your doctor may recommend diagnostic tests and evaluations, which may include:

• Colonoscopy: Colonoscopy is the gold standard for diagnosing colon cancer and allows for direct visualisation of the colon and rectum using a flexible, lighted tube with a camera (colonoscope). During colonoscopy, the doctor can detect polyps, tumours, or other abnormalities, and may perform biopsies or remove polyps for further evaluation.
• Faecal Occult Blood Test (FOBT): FOBT is a stool-based test that detects hidden (occult) blood in the stool, which may indicate the presence of colorectal cancer or precancerous polyps. FOBT is often used as a screening test for colon cancer in asymptomatic individuals.
• Faecal Immunochemical Test (FIT): FIT is a newer stool-based test that detects human haemoglobin, a protein found in blood, in the stool. FIT is more specific for detecting colorectal cancer and has fewer false-positive results compared to traditional FOBT.
• CT Colonography (Virtual Colonoscopy): CT colonography is a non-invasive imaging test that uses computed tomography (CT) scans to create detailed images of the colon and rectum. CT colonography may be used as an alternative to colonoscopy for colorectal cancer screening or for further evaluation of abnormal findings.
• Flexible Sigmoidoscopy: Flexible sigmoidoscopy is a procedure that allows for visualization of the lower portion of the colon and rectum using a flexible, lighted tube with a camera (sigmoidoscope). While flexible sigmoidoscopy does not examine the entire colon like colonoscopy, it may be used to evaluate the rectum and left side of the colon for abnormalities.
• Barium Enema: Barium enema is a radiographic imaging test that uses contrast material (barium) and X-rays to visualize the colon and rectum. While less commonly used today compared to colonoscopy or CT colonography, barium enema may be recommended in certain situations, such as when colonoscopy is not feasible or if further evaluation is needed after abnormal findings on other tests.
• Biopsy: If suspicious lesions or abnormalities are detected during colonoscopy or other imaging tests, a biopsy may be performed to obtain tissue samples for microscopic examination. Biopsy is the definitive diagnostic test for colon cancer and helps determine the type, grade, and extent of the tumour.

Staging and Evaluation

Once a diagnosis of colon cancer is confirmed, further staging and evaluation may be performed to determine the extent of the disease and guide treatment decisions. Staging may include:

• Imaging Studies: Imaging studies such as CT scan, MRI, PET scan, or chest X-ray may be performed to evaluate the size, location, and spread of the tumour, detect metastases, or assess involvement of nearby structures.
• Laboratory Tests: Blood tests such as complete blood count (CBC), liver function tests, carcinoembryonic antigen (CEA), or other tumour markers may be ordered to assess for signs of anaemia, liver dysfunction, or tumour activity.
• Pathologic Evaluation: Pathologic examination of biopsy specimens or surgical specimens provides information about the histologic type, grade, depth of invasion, lymph node involvement, and presence of metastases, which are important factors for determining prognosis and treatment planning.

Treatment and Management

Treatment for colon cancer depends on various factors, including the stage, grade, location, size, and extent of the tumour, as well as the patient’s age, overall health, and preferences. Treatment options may include:

• Surgery: Surgical removal of the tumour and surrounding tissues (resection) is the primary treatment for early-stage colon cancer. Depending on the size, location, and stage of the tumour, different surgical approaches may be used, including local excision, segmental colectomy, or total colectomy with or without lymph node dissection.
• Chemotherapy: Chemotherapy uses drugs to kill cancer cells or inhibit their growth and may be used as adjuvant therapy (after surgery) or neoadjuvant therapy (before surgery) to reduce the risk of recurrence, shrink tumours, or improve treatment outcomes. Chemotherapy may be administered intravenously or orally and may be combined with other treatments such as surgery or radiation therapy.
• Radiation Therapy: Radiation therapy uses high-energy beams of radiation to destroy cancer cells or shrink tumours and may be used in combination with surgery or chemotherapy for locally advanced or metastatic colon cancer. Radiation therapy may be delivered externally (external beam radiation therapy) or internally (brachytherapy) to target the tumour and surrounding tissues.
• Targeted Therapy: Targeted therapy drugs target specific molecular pathways or genetic mutations involved in colon cancer growth and progression and may be used alone or in combination with other treatments to inhibit tumour growth, prevent angiogenesis (formation of new blood vessels), or overcome resistance to chemotherapy. Targeted therapy drugs may include monoclonal antibodies, tyrosine kinase inhibitors, or other molecularly targeted agents.
• Immunotherapy: Immunotherapy drugs such as immune checkpoint inhibitors or adoptive cell therapy may be used to stimulate the immune system to recognize and attack cancer cells. Immunotherapy may be used in certain cases of advanced or metastatic colon cancer to enhance treatment response, improve survival, or induce durable remissions.
• Clinical Trials: Participation in clinical trials may offer access to novel treatments, experimental therapies, or investigational drugs that are being evaluated for safety and efficacy in the treatment of colon cancer. Clinical trials help advance scientific knowledge and may provide potential benefits to participants.

Follow-Up and Monitoring

After treatment for colon cancer, regular follow-up visits with your doctor, gastroenterologist, oncologist, or colorectal surgeon are essential to monitor treatment response, assess disease recurrence, and address any complications or side effects. Monitoring may include:

• Colonoscopy: Periodic colonoscopies may be performed to monitor for recurrence, detect new polyps or tumours, or assess the health of the colon and rectum following treatment.
• Imaging Studies: Follow-up imaging studies such as CT scan, MRI, or PET scan may be ordered to evaluate for recurrence, detect metastases, or assess treatment response.
• Blood Tests: Blood tests such as CEA (carcinoembryonic antigen) or other tumour markers may be monitored periodically to assess for signs of disease recurrence or progression.
• Physical Examination: Regular physical examinations, including abdominal palpation, digital rectal examination (DRE), or pelvic examination, may be performed to assess for signs of recurrence or metastases.
• Symptom Assessment: Your doctor will ask about any changes in symptoms, such as abdominal pain, rectal bleeding, changes in bowel habits, or unexplained weight loss, during follow-up visits.

Prevention and Screening

Prevention and early detection are key strategies for reducing the risk of colon cancer and improving outcomes. Lifestyle modifications, dietary interventions, and screening tests can help prevent or detect colon cancer at an early stage when it is most treatable. Strategies for prevention and screening may include:

• Healthy Lifestyle: Adopting a healthy lifestyle that includes regular physical activity, maintaining a healthy weight, avoiding smoking, limiting alcohol consumption, and eating a balanced diet rich in fruits, vegetables, whole grains, and fiber may help reduce the risk of colon cancer.
• Screening Tests: Screening tests such as colonoscopy, sigmoidoscopy, faecal occult blood test (FOBT), faecal immunochemical test (FIT), or stool DNA test may be recommended for individuals at average or increased risk of colon cancer. Screening tests can help detect precancerous polyps or early-stage cancer and allow for timely intervention or treatment.
• Colonoscopy: Colonoscopy is the most effective screening test for colon cancer and is recommended for average-risk individuals starting at age 50 (earlier for individuals at increased risk). Colonoscopy allows for visualization of the entire colon and rectum and enables detection and removal of precancerous polyps or early-stage cancer.
• Sigmoidoscopy: Flexible sigmoidoscopy is a screening test that allows for visualization of the lower portion of the colon and rectum and may be used as an alternative to colonoscopy for some individuals. While flexible sigmoidoscopy does not examine the entire colon, it can detect abnormalities in the rectum and left side of the colon.
• Stool-Based Tests: Stool-based tests such as FOBT, FIT, or stool DNA test may be used as non-invasive screening tests for colon cancer. These tests detect blood or genetic changes in the stool that may indicate the presence of colorectal cancer or precancerous polyps.
• Genetic Testing: Genetic testing may be recommended for individuals with a family history of colon cancer, certain genetic syndromes, or other risk factors to assess their risk of developing the disease. Genetic counselling and testing can help identify individuals at increased risk and guide personalized screening and preventive strategies.

Conclusion

Colon cancer is a common malignancy that develops in the colon or rectum and affects millions of individuals worldwide.

While the exact cause of colon cancer is not fully understood, it is believed to involve a complex interplay of genetic, environmental, lifestyle, and dietary factors.

Colon cancer typically arises from precancerous polyps and may not cause symptoms in its early stages, highlighting the importance of screening and early detection.

If diagnosed with colon cancer, treatment options may include surgery, chemotherapy, radiation therapy, targeted therapy, immunotherapy, or participation in clinical trials.

Prevention strategies such as healthy lifestyle habits, dietary modifications, and regular screening tests can help reduce the risk of colon cancer and improve outcomes.

By working closely with doctors, staying informed about prevention and screening recommendations, and adopting healthy behaviours, individuals can reduce their risk of colon cancer and improve their overall health and well-being.

Arranging To Visit A Private GP

To discuss any worrying symptoms that could be an indication of colon cancer make an appointment with one of our private GPs. Appointments are available to everyone and can often be booked for the same day. There is no need to be registered with our Buckinghamshire hospital, or live locally.

If you have insurance which covers a GP visit, we can in most cases invoice the insurer directly. Where you are paying directly, the cost for a 30 minute consultation is £125.

Any additional costs will always be discussed. They could apply if you are referred for an MRI scan, or to a consultant, or for other agreed decisions to support your health.

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