- Age: Risk of colorectal cancer increases significantly after age 50, with most cases diagnosed in people aged 60 and older.
- Family History: Having a first-degree relative with colorectal cancer may double the risk of developing the disease.
- Genetic Syndromes: Inherited conditions such as Lynch syndrome and familial adenomatous polyposis significantly increase colorectal cancer risk.
- Lifestyle Factors: A diet high in processed meats and low in fibre, physical inactivity, obesity, smoking, and regular alcohol consumption contribute to increased risk.
- Medical History: Previous colorectal polyps, inflammatory bowel disease, or type 2 diabetes can increase the risk of developing colorectal cancer.
- Radiation Exposure: Previous radiation therapy to the abdomen or pelvis for other cancers may increase the risk.
Colorectal Cancer
Dr Chong Choon Seng
MBBS | MRCS | Masters in Medicine (Surgery) | FRCS (Edinburgh)
Colorectal cancer develops in the large intestine (colon) or rectum when cells begin to grow abnormally and form tumours. This cancer typically starts as small, benign clusters of cells called polyps that can become cancerous over time. The disease affects the body’s ability to digest food and remove waste, and may spread to other organs if not treated.
Symptoms of Colorectal Cancer
The following symptoms may indicate the presence of colorectal cancer, though they can also be caused by other conditions:
- Changes in Bowel Habits: A persistent change lasting more than three weeks, including alternating diarrhoea and constipation or changes in stool consistency.
- Blood in Stool: Bright red or very dark blood in the stool, which may appear mixed with the stool or coating it.
- Unexplained Weight Loss: Losing weight without changes to diet or exercise habits over a period of several weeks to months.
- Persistent Abdominal Pain: Regular discomfort, bloating, or pain in the lower abdomen, especially if accompanied by other symptoms.
- Fatigue: Ongoing tiredness and weakness that persists despite adequate rest, often due to blood loss or the cancer’s effects on the body.
- Anaemia: A reduction in red blood cells that may cause shortness of breath, pale skin, and increased fatigue.
Causes and Risk Factors
Several factors can increase the likelihood of developing colorectal cancer:
Types of Colorectal Cancer
Colorectal cancer presents in several forms, each affecting different parts of the large intestine or having distinct characteristics.
Adenocarcinoma
Makes up approximately 95% of colorectal cancers. This cancer begins in the cells that produce mucus to lubricate the inside of the colon and rectum. Adenocarcinomas typically start as polyps in the intestinal lining and can grow into the wall of the colon or rectum over time.
Squamous Cell Carcinoma
Develops in the rectum from the flat cells that line the anal canal. This type accounts for a small percentage of colorectal cancers and often requires different treatment approaches than adenocarcinomas. Treatment typically involves a combination of chemotherapy and radiation.
Carcinoid Tumours
These rare tumours start in hormone-producing cells in the intestine. Carcinoid tumours grow slowly and may produce hormones that cause distinct symptoms. They often appear as small, yellow-coloured growths and can be multiple in number.
Gastrointestinal Stromal Tumours (GISTs)
These uncommon tumours begin in specialised cells in the wall of the colon called interstitial cells of Cajal. GISTs can occur anywhere in the digestive tract but rarely appear in the colon. They may require targeted therapy rather than traditional cancer treatments.
Diagnostic Methods
Medical professionals employ various diagnostic methods to detect and evaluate colorectal cancer, often using multiple approaches for accuracy:
Colonoscopy
A long, flexible tube with a camera examines the entire colon and rectum. During this procedure, your colorectal surgeon can remove suspicious polyps and take tissue samples for biopsy. The examination typically takes 30-60 minutes and requires bowel preparation beforehand.
CT Colonography
This advanced imaging technique creates detailed cross-sectional images of the colon and rectum. The procedure uses X-rays and computer technology to produce 3D images that can detect polyps and other abnormalities without inserting a scope into the colon.
Biopsy
Tissue samples taken during a colonoscopy undergo microscopic examination. The pathologist examines the cells’ structure and arrangement to determine if cancer is present and, if so, its grade and characteristics. This information helps guide treatment decisions.
Blood Tests
CEA (Carcinoembryonic Antigen) levels and other blood markers can help track cancer progression and treatment response. Regular monitoring of these markers can indicate whether treatment is working or if the cancer has returned after treatment.
Imaging Studies
MRI scans, CT scans, and PET scans help determine if the cancer has spread beyond the colon. These tests create detailed images of organs and tissues to identify potential metastases and guide treatment planning.
Treatment Options
Treatment for colorectal cancer depends on the cancer’s stage, location, and the patient’s overall health. Multiple approaches may be used together for optimal results.
Non-Surgical Treatment
- Chemotherapy: Powerful drugs target rapidly dividing cancer cells throughout the body. Treatment typically occurs in cycles over several months, with rest periods between treatments to allow the body to recover. Side effects can include fatigue, nausea, and increased risk of infection.
- Radiation Therapy: High-energy beams target and destroy cancer cells in specific areas. This treatment often combines external beam radiation with internal radiation methods. Sessions typically occur five days per week for several weeks, with each session lasting about 15 minutes.
- Targeted Therapy: This type of treatment focuses on specific abnormalities within cancer cells. They can block growth signals, prevent formation of new blood vessels, or deliver toxic substances directly to cancer cells. Treatment duration varies based on the specific drug and response.
Surgical Treatment
- Polypectomy: Early-stage cancers within a polyp may be removed during a colonoscopy. The procedure involves removing the polyp with special tools inserted through the colonoscope. Recovery typically takes only a few days.
- Colectomy: Surgical removal of part or all of the colon, along with nearby lymph nodes. The surgeon reconnects the healthy portions of the bowel or creates a temporary or permanent opening (stoma) in the abdominal wall for waste elimination. Recovery usually requires 4-6 weeks.
- Low Anterior Resection: Removes rectal cancers through an abdominal incision. The procedure preserves the anal sphincter when possible, allowing normal bowel function to continue. Recovery involves a hospital stay of 5-7 days and several weeks of home recovery.
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Prevention and Management
Reducing colorectal cancer risk involves following bowel cancer screening programmes and attending regular check-ups as recommended by your colorectal cancer specialist. A diet rich in vegetables, fruits, and whole grains, combined with regular physical activity, helps maintain bowel health. Limiting red meat consumption, avoiding processed meats, maintaining a healthy weight, and avoiding tobacco and excessive alcohol support prevention.
For those diagnosed with colorectal cancer, management includes following medical advice, attending follow-up appointments, maintaining proper nutrition during treatment, and participating in recommended exercise programmes when cleared by your colorectal cancer specialist. Regular monitoring helps detect any signs of recurrence early.
Frequently Asked Questions
Can colorectal cancer affect young adults?
While most cases occur in people over 50, colorectal cancer cases among young adults have increased. People under 50 should discuss any persistent symptoms with their colorectal cancer specialist, particularly if they have a family history of the disease or other risk factors.
How often should screening begin?
Colorectal cancer screening typically starts at age 45 for those at average risk and is repeated every 10 years with a colonoscopy or more frequently with stool tests. People with a family history or certain conditions may need to start earlier, around age 40. Consult your colorectal surgeon to determine the best screening plan for you.
What dietary changes help during treatment?
During treatment, patients often benefit from smaller, frequent meals that are easily digestible. Foods high in protein support healing, while staying hydrated helps manage treatment side effects. A registered dietitian can provide personalised dietary recommendations based on individual needs and treatment plans.
How does a stoma affect daily life?
Many people with stomas return to their regular activities, including work, exercise, and social events. Modern stoma appliances are discreet and secure, allowing for normal movement and activities. Stoma care nurses provide support and education for managing the stoma effectively in daily life.
What follow-up care is needed after treatment completion?
After treatment, patients typically follow a structured surveillance schedule including regular physical examinations, blood tests, and imaging studies. The frequency of follow-up appointments gradually decreases over time if no signs of recurrence appear. Most follow-up programmes continue for at least five years after treatment.
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Dr Chong Choon Seng
MBBS (NUS)
MRCS (Edinburgh)
Masters in Medicine (Surgery)(NUS)
FRCS (Edinburgh)
Dr Chong is the former Program Director of General Surgery Residency at NUHS, and has more than 10 years of experience as a colorectal and general surgeon.
As an esteemed professional in minimally invasive surgery, Dr. Chong remains committed to achieving optimal outcomes for all surgical conditions, from piles to cancer treatment.
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