Colorectal Cancer

Bowel cancer, also known as colorectal cancer, is a cancer that starts in the large intestine, which includes the colon and rectum. It usually develops slowly over several years, often beginning as a benign polyp (a small growth on the bowel lining) that later turns cancerous.

It is one of the most common cancers worldwide and a major cause of cancer-related deaths, but early detection makes it highly treatable and often curable.

Bowel cancer arises when normal cells in the lining of the colon or rectum undergo genetic mutations, leading to uncontrolled growth. These abnormal cells can invade nearby tissues and may spread (metastasize) to lymph nodes, liver, lungs, or other organs.

Most cases occur in people over 50, but rates are increasing in younger adults, partly due to lifestyle and dietary factors.

Types

• Adenocarcinoma (≈95%)
  Originates from mucus-producing gland cells in the bowel lining.

• Mucinous adenocarcinoma
  Produces large amounts of mucus; may behave more aggressively.

• Signet ring cell carcinoma
  Rare and aggressive; usually diagnosed at a later stage.

• Neuroendocrine tumors (NETs)
  Arise from hormone-producing cells.

• Lymphoma / Sarcoma
  Very rare forms involving immune or connective tissue.

Stages

Risk Factors

• Age over 50

• Family history of bowel cancer or polyps

• Inflammatory bowel disease (ulcerative colitis, Crohn’s disease)

• Diet high in red or processed meat

• Low fiber intake

• Obesity and physical inactivity

• Smoking and excessive alcohol intake

• Type 2 diabetes

• Genetic syndromes (e.g. FAP, Lynch syndrome)

Symptoms

• Persistent change in bowel habits (diarrhea or constipation)

• Blood in stool or rectal bleeding

• Abdominal pain, bloating, or cramps

• Unexplained weight loss

• Fatigue or weakness (often due to anemia)

• Feeling of incomplete bowel emptying

Diagnosis

1. Colonoscopy (gold standard) – allows direct visualization and biopsy

2. Biopsy – confirms cancer type

3. CT scan / MRI – staging and spread assessment

4. Blood tests – anemia, liver function

5. CEA tumor marker – used for monitoring, not screening

6. FIT / FOBT – screening tests for hidden blood in stool

Facts (FAQ)

Q1: Is bowel cancer preventable?
Many cases can be prevented with regular screening and healthy lifestyle choices.

Q2: At what age should screening start?
Usually from age 45–50, earlier if there’s a family history.

Q3: Is bowel cancer curable?
Yes — especially when detected early. Stage I survival rates exceed 90%.

Q4: Does blood in stool always mean cancer?
No, but it should never be ignored.