Colon/ Coloractel Cancer
The Function of the Colon and Complications Associated with Colorectal Cancer
The colon, also known as the large intestine, plays a crucial role in the digestive system. Its primary functions include the absorption of water and salts from the material that has not been digested as food, and the formation and excretion of feces. The colon also houses beneficial bacteria that aid in digestion and produce essential vitamins like vitamin K.
When colorectal cancer (CRC)—which includes cancers of the colon and rectum—develops, it significantly disrupts these vital processes. It may cause bleeding, absorption dysfunction, obstruction, or even perforation of the colon wall. Advanced cases may lead to bowel obstruction, metastatic spread (especially to the liver or lungs), cachexia (wasting syndrome), and systemic metabolic deterioration. The presence of cancer in the colon can also impair nutritional status, immune function, and overall quality of life.
Categories Associated with Primary and Secondary Colorectal Tumours
Colorectal cancer may be classified under two broad categories:
Primary Colorectal Cancer
This originates in the tissues of the colon or rectum. The most prevalent type is adenocarcinoma, which starts in the mucus-producing glands lining the colon or rectum. Other less common types include:
Mucinous adenocarcinoma
Signet-ring cell carcinoma
Squamous cell carcinoma
Gastrointestinal stromal tumors (GIST)
Neuroendocrine tumors
Secondary (Metastatic) Colorectal Cancer
These are cancers that began in another part of the body (such as the breast, stomach, or pancreas) and have spread (metastasized) to the colon or rectum. Conversely, colorectal cancer often metastasizes to the liver, lungs, peritoneum, or bones.
Causes and Risk Factors
Several factors contribute to the development of colorectal cancer, often over many years. These include:
Age: Risk increases significantly after age 50
Genetics: Family history, Lynch syndrome, and Familial Adenomatous Polyposis (FAP)
Diet: High intake of red or processed meats, low fiber intake
Inflammatory bowel diseases: Crohn’s disease and ulcerative colitis
Obesity and physical inactivity
Smoking and heavy alcohol use
Type 2 diabetes
History of polyps or previous colorectal cancer
Radiation therapy to the abdomen or pelvis
Signs and Symptoms of Colorectal Cancer
Colorectal cancer is often asymptomatic in early stages, making regular screening essential. As it progresses, symptoms may include:
Persistent changes in bowel habits (constipation, diarrhea, or narrowing of stool)
Blood in stool or rectal bleeding
Abdominal pain, cramping, bloating, or discomfort
Fatigue or generalized weakness
Unexplained weight loss
A feeling that the bowel does not empty completely
Anemia-related symptoms due to chronic blood loss
Nausea or vomiting in advanced cases
Diagnosis of Colorectal Cancer
Diagnosis involves a combination of clinical assessments and diagnostic tools:
Medical History and Physical Examination
Digital Rectal Exam (DRE)
Fecal Tests:
Fecal Immunochemical Test (FIT)
Fecal Occult Blood Test (FOBT)
Stool DNA test (e.g., Cologuard)
Endoscopic Evaluation:
Colonoscopy (gold standard)
Sigmoidoscopy
Biopsy (during colonoscopy)
Imaging Studies:
CT colonography (virtual colonoscopy)
Abdominal/pelvic CT or MRI
PET scans for staging
Laboratory Tests:
Complete Blood Count (CBC)
Liver Function Tests
CEA (Carcinoembryonic Antigen) levels – a tumor marker
Staging:
Cancer staging (Stage 0–IV) using the TNM system helps in treatment planning and prognosis evaluation.
Best Treatment for Colorectal Cancer
Treatment depends on the cancer’s location (colon or rectum), size, stage, and patient’s overall health.
A. Traditional Treatments
1. Surgical Procedures
Polypectomy: For very early-stage cancers confined to polyps
Partial Colectomy: Removing the section of the colon with cancer
Total Colectomy: In cases with widespread disease
Colostomy/Ileostomy: If reconnection isn’t possible
Rectal Surgery: For cancers in the lower rectum, possibly requiring resection with anastomosis or permanent stoma
2. Radiation Therapy
Commonly used for rectal cancer, either before surgery to shrink tumors or after surgery to kill remaining cells
External beam radiation therapy is the standard method
3. Systemic Chemotherapy
Used after surgery (adjuvant), before surgery (neoadjuvant), or for metastatic disease
Common drugs include:
5-FU (Fluorouracil)
Oxaliplatin
Capecitabine
Irinotecan
Side effects: fatigue, diarrhea, low blood count, neuropathy
B. Advanced and Alternative Treatments for Colorectal Cancer
1. Minimally Invasive and Microinvasive Therapies
Laparoscopic or Robotic Surgery: Less invasive surgeries with faster recovery
Radiofrequency Ablation (RFA) and Microwave Ablation (MWA) for liver metastases
Cryoablation for localized tumors
2. Targeted Therapy
Monoclonal antibodies against specific molecules:
Bevacizumab (targets VEGF – blood vessel growth)
Cetuximab, Panitumumab (targets EGFR – cell growth)
Fewer side effects than traditional chemotherapy
3. Immunotherapy
Primarily used in MSI-H/dMMR tumors (Microsatellite Instability-High / Deficient Mismatch Repair)
Drugs include:
Pembrolizumab (Keytruda)
Nivolumab + Ipilimumab
Reprograms immune system to attack cancer without harming healthy cells
4. Brachytherapy and Radioembolization
Used mainly for rectal or liver metastases
Radioactive beads deliver localized radiation to tumor tissue while sparing normal tissue
5. Stem Cell and Future Therapies
Experimental use of CAR-T Cell Therapy and stem-cell-mediated immune restoration is being studied for resistant forms of CRC
Prevention and Lifestyle Management
Preventing colorectal cancer involves reducing risk factors and early detection:
Regular Screening: Begin at age 45, earlier if high risk
Diet: High in fiber, fruits, vegetables; low in red/processed meats
Exercise: At least 30 minutes of physical activity most days
Avoid Alcohol and Smoking
Maintain Healthy Weight
Treat Chronic Diseases: Proper management of IBD and diabetes
Prophylactic Surgery: In patients with hereditary cancer syndromes
Aspirin Use: May reduce risk (under medical advice)
Prognosis and Survival Rates
Prognosis depends on the stage at diagnosis and response to treatment:
Stage I: 90–95% 5-year survival
Stage II: 70–85%
Stage III: 50–70%
Stage IV (metastatic): ~10–15%
Survival rates have improved with advanced screening, targeted therapies, and earlier interventions. Regular follow-up is crucial to detect recurrence or metastasis early.
Conclusion
Colorectal cancer, encompassing both colon and rectal malignancies, remains a significant cause of cancer morbidity and mortality globally. Understanding its risk factors, promoting early detection through regular screenings, and implementing comprehensive treatment strategies—ranging from surgery to advanced immunotherapies—can significantly enhance survival outcomes. Public awareness and proactive lifestyle choices are essential in reducing the burden of this preventable disease.