Colon Cancer: A Patient’s Guide

Colon cancer begins in the large intestine and can spread to other parts of the body, necessitating prompt treatment. While it most commonly affects people over 50, factors like family history, lifestyle, and genetics can increase risk at any age. Symptoms, including changes in bowel habits or abdominal discomfort, often appear late, making early screening necessary. This article provides an overview of colon cancer, covering its risk factors, symptoms, screening methods, treatment options, and prevention steps.

Recognising the Symptoms of Colon Cancer

Colon cancer often develops without any symptoms in its early stages. As the cancer grows, symptoms may begin to appear. Common symptoms include:

Changes in Bowel Habits

Tumours can partially block the colon, resulting in persistent diarrhoea, constipation, or the sensation of incomplete bowel movements because they interfere with normal stool passage.

Blood in Stool  

As the tumour grows, it may erode nearby blood vessels, leading to bleeding. This blood may appear as red or dark streaks in the stool and is often mistaken for conditions like haemorrhoids.

Abdominal Discomfort  

Tumours can cause pain, cramping, and bloating by pressing on surrounding tissues. They may also cause a feeling of fullness after eating small amounts because they disrupt the normal movement of food through the digestive tract.

Unexplained Weight Loss and Fatigue  

Sudden weight loss without dietary changes may be a sign of cancer. Additionally, anaemia from blood loss or metabolic changes caused by the tumour can cause persistent fatigue.

What Causes Colon Cancer? Key Risk Factors

There are several known risk factors for colon cancer, including both lifestyle and genetic components:

Age 

Colon cancer is more common in people over the age of 50, but it can occur at any age. The risk generally increases with age.

Family History and Genetics  

A family history of colon cancer or inherited genetic syndromes, such as Lynch syndrome or familial adenomatous polyposis (FAP), significantly raises the risk. These genetic factors contribute to an increased tendency for abnormal cell growth in the colon.

Diet and Lifestyle  

A diet high in red or processed meats, low in fibre, and high in fat has been associated with an increased risk of colon cancer. Lifestyle factors such as physical inactivity, obesity, smoking, and excessive alcohol consumption are also linked to an increased risk.

Chronic Inflammatory Conditions  

Chronic inflammatory bowel diseases, such as ulcerative colitis and Crohn’s disease, can cause long-term inflammation in the colon, which may lead to changes in cell growth and increase the risk of cancer.

Types of Colon Cancer

Colon cancer is classified into several types, which differ in how they originate and respond to treatment. These variations affect growth patterns and influence treatment approaches.

Adenocarcinoma  

This is the most common type, developing in the gland cells lining the colon. Most colon cancers are adenocarcinomas.

Carcinoid Tumours  

Carcinoid tumours are rare and arise from hormone-producing cells in the colon. These tend to grow slowly and may go undetected until they reach an advanced stage.

Gastrointestinal Stromal Tumours (GISTs)  

GISTs originate from specific cells in the digestive tract and are rare in the colon. They can be either benign or malignant (spreads to other parts of the body), with variable growth behaviour.

Lymphoma  

Lymphoma in the colon begins in immune cells and is uncommon. It usually appears in later stages, presenting symptoms similar to other colon cancers.

Stages of Colon Cancer: What They Mean

Colon cancer staging describes how far the cancer has spread in the body. Each stage requires different treatments and affects the chances of long-term survival. Knowing the stage helps doctors choose the most appropriate treatment plan.

• Stage 0: Cancer is in the innermost lining of the colon and has not spread. It is highly localised and very treatable.

• Stage I: Cancer has grown deeper into the layers of the colon wall but remains within the colon and has not spread to lymph nodes. Surgery is often effective at this stage.

• Stage II: Cancer has spread through the wall of the colon but has not reached lymph nodes or other parts of the body. Treatment may include surgery and chemotherapy.

• Stage III: Cancer has reached nearby lymph nodes but not other organs. Treatment usually involves surgery, chemotherapy, and sometimes radiation.

• Stage IV: Cancer has spread to distant organs like the liver or lungs. This advanced stage may require a combination of surgery, chemotherapy, and targeted therapies.

Screening and Diagnosis

Screening is necessary as it can detect cancer early, even before symptoms appear, improving treatment outcomes. Standard screening methods include:

Colonoscopy  

This procedure uses a long, flexible tube with a camera to thoroughly examine the entire colon for abnormalities. It allows doctors to directly view the colon lining and identify any signs of cancer or other issues. During the procedure, any polyps (precancerous growths) found can be removed immediately, reducing cancer risk.

Stool-Based Tests  

These non-invasive tests, known as the faecal occult blood test (FOBT) or the faecal immunochemical test (FIT), detect hidden blood in the stool, which can be an early indicator of colon cancer. In some cases, faecal DNA tests may be used to identify genetic markers linked to colon cancer.

Imaging Tests  

CT colonography (also known as virtual colonoscopy), CT scans, and MRI scans can detect tumours and determine whether the cancer has spread to nearby tissues or organs. These imaging tests provide detailed cross-sectional views of the colon, assisting in staging and treatment planning.

If a screening test produces a positive result, additional diagnostic procedures, such as a biopsy, may be required to confirm the presence of cancer cells. 

Treatment Options for Colon Cancer

Treatment for colon cancer depends on the stage of the disease, the type of tumour, and the patient’s overall health. Treatment may involve one or a combination of the following approaches:.

Non-Surgical Treatment

Chemotherapy  

Chemotherapy uses drugs to target and destroy rapidly dividing cancer cells. It is often given after surgery to eliminate any remaining cancer cells and reduce the risk of recurrence. In cases where the cancer has spread (metastasised), chemotherapy can help control tumour growth and manage symptoms by slowing down the disease progression.

Radiation Therapy  

Radiation therapy uses high-energy rays focused on the tumour to kill or shrink cancer cells. It is typically used for cancers in the lower colon or rectum and is often combined with chemotherapy for greater effect. Radiation can help reduce tumour size, making surgical removal easier, and may also relieve symptoms in advanced cases.

Targeted Therapy 

Targeted therapy drugs disrupt specific molecules that promote cancer cell growth and spread. In colon cancer, these drugs work by cutting off the tumour’s blood supply or blocking growth signals. This method, typically used for advanced-stage cancer, aims to minimise harm to healthy cells while also reducing side effects when compared to chemotherapy.

Immunotherapy  

Immunotherapy boosts the immune system’s ability to recognise and attack cancer cells. This treatment, which is effective in certain colon cancers with specific genetic mutations, can slow or shrink tumour growth by assisting the immune system in more effectively targeting cancer cells.

Surgical Treatment

Polypectomy and Local Excision 

In early-stage colon cancers, tumours may be small and confined to the inner layers of the colon. During a colonoscopy, these tumours or polyps can be removed in a procedure known as a polypectomy or local excision, which involves excising the tumour without major surgery. This method may treat early cancer and reduce the risk of further spread.

Colectomy  

A colectomy is used to remove part or all of the affected section of the colon in cases of larger or more advanced tumours. This surgery is intended to remove the tumour as well as any nearby lymph nodes where cancer may have spread. Removing lymph nodes also allows doctors to examine them for cancer cells, which helps in assessing the stage of the disease and planning further treatment.

Preventing Colon Cancer

Preventive measures for colon cancer focus on lifestyle changes and regular screenings. A balanced diet rich in fruits, vegetables, and whole grains, along with regular exercise, can help lower risk. Avoiding smoking and limiting alcohol consumption are also necessary precautions. 

For those with a family history of colon cancer or genetic predispositions, genetic testing and starting screenings at an earlier age may be recommended. Regular screenings, such as colonoscopies, are one of the most effective ways to detect and prevent colon cancer by identifying and removing precancerous polyps early.

Conclusion

Colon cancer is influenced by genetic, lifestyle, and environmental factors. Recognising symptoms, understanding risk factors such as age, family history, and lifestyle, and getting regular screenings are key for early detection and effective treatment. Screening is generally recommended starting at age 50 or earlier for those at higher risk. Staying informed about symptoms, risk factors, and prevention options helps you make proactive health decisions with your healthcare provider.

Schedule a consultation today to discuss the best screening and prevention options for you.