One of the most common gastrointestinal cancers, colon cancer is a multifactorial disease process with genetic etiological factors. Inflammation of the digestive tract, environmental exposure and dietary choices are also some circumstances for colon cancer. Colorectal cancer is a progressive, complex disease. Starting as a premalignant lesion it advances into invasive adenocarcinoma.

Causes

There are several factors that lead to the cause of colorectal cancer:

• Inflammatory bowel diseases like ulcerative colitis and Crohn’s disease
• Hereditary mutations of the APC gene
• HNPCC or hereditary nonpolyposis colon cancer syndrome
• Diet with a high content of red meat, low-fibre diets, and poor intake of fruits and vegetables
• Obesity
• Smoking
• Alcohol abuse
• Sedentary lifestyle

Signs and Symptoms

• Marked changes in bowel habits – diarrhoea, constipation, change in stool consistencies
• Rectal bleeding
• Persistent abdominal cramps
• Sudden weight loss
• Fatigue

Diagnosis

• Physical examination reveals macroscopic rectal bleeding, tenderness in the abdomen, palpable abdominal mass, ascites and hepatomegaly. Clinical presentations also include abdominal pain, intestinal obstruction and iron-deficiency anaemia. Left-sided tumours usually present as bowel obstructions and right-sided lesions can cause diarrhoea and bleeding.
• Blood studies will include a complete blood count (CBC), liver function tests, serum chemistries, renal function tests, serum carcinoembryonic antigen levels
• Imaging of the chest and abdomen is obtained to stage the cancer
• CT of the abdomen and pelvis, ultrasound of the abdomen and liver and MRI scans are conducted; PET-CT scan to detect metastatic deposits is done.
• Screening tests will help the detection of adenomatous polyps
• Capsule colonoscopy is performed
• Postpolytectomy surveillance for patients with previous detections of adenomas
• Molecular testing of the tumour

Treatment and Medication
Surgery is the primary curative modality available for colorectal cancer. The primary tumour is removed along with areas of lymphatic drainage. Resection is the best-known treatment for colon cancer. Cryotherapy also uses probes to freeze the tumour. Radiofrequency ablation or RFA techniques are used to heat the tumour and its surrounding margins causing coagulation necrosis. Stage II and III cancer may require chemotherapy using 5-fluorouracil with adjuncts like levamisole and leucovorin. Biological agents such as bevacizumab, cetuximab and Zaltrap are used as antibody therapies. Rectal cancers are often treated with radiation therapy.

We offer consultations for early-stage colorectal cancers that require surgery. It is suitable to obtain a consultation after diagnosis and staging of the cancer, for which resection is the appropriate treatment.