Colon Cancer: Causes, Symptom and Treatment

What is Colon Cancer?

Ever heard of a disease that grows quietly in your gut, sometimes for years, without making much noise? That’s colon cancer. Also known as colorectal cancer (when it involves both the colon and rectum), this is a condition where abnormal cells grow uncontrollably in the large intestine. It’s like a weed in a garden—it starts small, often as a benign polyp, but if left unchecked, it can grow aggressively and spread.

Colon cancer is one of the most common cancers worldwide. According to the World Health Organization (WHO), it ranks third in terms of cancer incidence globally and is the second leading cause of cancer death. Men and women are equally at risk, and while it usually strikes after the age of 50, it’s becoming increasingly common among younger adults too.

How Does It Occur?

Let’s picture the colon like a long pipe that helps absorb water and salt from digested food. Now imagine tiny bumps (polyps) forming on the inner lining of this pipe. Most are harmless, but some of them—especially adenomatous polyps—can undergo DNA mutations over time. These changes act like a green light for uncontrolled cell growth, eventually forming a malignant tumor.

Think of it like rust slowly eating through a metal pipe—at first it’s just surface damage, but given time, it weakens the whole system.

What Are the Causes of Colon Cancer?

While there’s no single cause, a combination of genetic and lifestyle factors usually plays a role.

• Sporadic cases (around 70%) arise randomly, without a strong family history. These often develop due to environmental factors and ageing.
• Hereditary causes (about 5-10%) involve gene mutations passed from parent to child, like:
  • Lynch Syndrome (HNPCC) – responsible for 2-4% of all colorectal cancers.
  • Familial Adenomatous Polyposis (FAP) – a rare but severe form causing hundreds of polyps.

Inflammatory bowel diseases like ulcerative colitis or Crohn’s disease also increase the risk significantly.

Who Is at Risk?

You might be wondering: Am I at risk? The truth is, we all are—but some more than others.

Here are key risk factors:

• Age over 50
• Diet high in red or processed meat
• Low fibre intake
• Sedentary lifestyle
• Obesity
• Smoking and heavy alcohol use
• Family history of colon cancer or polyps
• History of IBD (inflammatory bowel disease)

The riskiest combo? A family history plus an unhealthy lifestyle. But even people with no risk factors can still get it—so don’t ignore your gut feelings.

Symptoms of Colon Cancer

Colon cancer can sneak in quietly, which is why routine screening is so crucial. But when symptoms appear, they may include:

• Blood in the stool (can be bright red or dark)
• Persistent changes in bowel habits (diarrhea, constipation, or feeling like the bowel doesn’t empty completely)
• Unexplained weight loss
• Fatigue
• Abdominal pain or cramping
• A lump or mass in the abdomen

Why do these symptoms happen? Tumors can bleed, block the intestine, or disrupt normal bowel function—hence the changes you feel.

Differential Diagnosis

Colon cancer shares symptoms with several other gastrointestinal conditions, which makes diagnosis tricky at times. Common conditions to consider include:

• Hemorrhoids – which also cause rectal bleeding
• Irritable Bowel Syndrome (IBS) – known for bowel habit changes but not linked to cancer
• Diverticulitis – inflammation of colon pouches that causes abdominal pain
• Colitis or Crohn’s disease – chronic inflammatory conditions
• Colonic polyps – benign growths that may resemble early-stage cancer

That’s why it’s essential not to jump to conclusions—or ignore symptoms. Only a proper medical evaluation can tell the difference.

How Is Colon Cancer Diagnosed?

The gold standard for diagnosing colon cancer is a colonoscopy. It’s a procedure where a long, flexible tube with a camera is inserted through the rectum to examine the entire colon.

• Polyps can be removed during the procedure, and if a suspicious mass is found, a biopsy is taken.
• If colonoscopy isn’t possible, CT colonography (a virtual colonoscopy) or sigmoidoscopy might be alternatives.
• Blood tests like CEA (carcinoembryonic antigen) help monitor the cancer, but not diagnose it.

Early detection through screening can literally save lives—colonoscopies can catch polyps before they turn cancerous.

Treatment of Colon Cancer

Treatment depends on the stage of the cancer. Here’s a breakdown:

1. Surgery – The Primary Approach

For early-stage colon cancer, removing the tumor through colectomy (colon resection) is often curative. Surgeons may remove part of the colon and nearby lymph nodes.

2. Chemotherapy

This is used:

• After surgery (adjuvant) to kill remaining cancer cells
• In advanced stages to slow down the cancer’s growth

Common drugs include:

• 5-FU (fluorouracil)
• Capecitabine
• Oxaliplatin
• Irinotecan

3. Radiation Therapy

Less commonly used for colon cancer (more for rectal cancer), but it may be helpful in certain advanced cases.

4. Targeted Therapy

For metastatic colon cancer, newer medications target specific cancer traits.

Examples:

• Bevacizumab (Avastin) – blocks blood supply to tumors
• Cetuximab and panitumumab – target the EGFR protein in cancer cells

5. Immunotherapy

For tumors with specific genetic features (like MSI-high), immunotherapy can boost the body’s ability to fight cancer. Drugs like pembrolizumab are game-changers in some cases.

When one treatment doesn’t work, doctors switch or combine therapies based on how the cancer behaves.

References

1. Colorectal Cancer – World Health Organization (WHO). https://www.who.int/news-room/fact-sheets/detail/cancer
2. American Cancer Society – What is Colorectal Cancer?. https://www.cancer.org/cancer/colon-rectal-cancer/about/what-is-colorectal-cancer.html
3. National Cancer Institute – Colon and Rectal Cancer Treatment (PDQ®). https://www.cancer.gov/types/colorectal/patient/colon-treatment-pdq
4. Colorectal Cancer Screening – U.S. Preventive Services Task Force (USPSTF). https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening
5. Genetics of Colorectal Cancer – National Human Genome Research Institute. https://www.genome.gov/Genetic-Disorders/Colorectal-Cancer