Colon Cancer - Early Signs, Risk Factors, Diagnosis, and Treatment Explained

Overview: What Is Colon Cancer?

Colon cancer begins in the colon, the largest section of the large intestine. It usually starts as small, noncancerous growths called polyps that slowly develop into cancer over time. Because this process can take years, colon cancer is often preventable through early screening and removal of polyps before they become dangerous.

In the United States, colon cancer is among the most common cancers diagnosed in both men and women. According to the American Cancer Society, thousands of new cases are reported every year, and it remains a leading cause of cancer-related deaths. However, when detected early, colon cancer is highly treatable, and many people go on to live full, healthy lives.

What Are the Types of Colon Cancer?

Colon cancer is not one single disease; there are different types based on the cells involved.

• Adenocarcinoma: The most common type, making up about 95% of cases. Begins in the glandular cells lining the colon that produce mucus and fluids.
• Carcinoid tumors: Develop from hormone-producing cells in the colon. Rare compared to adenocarcinoma.
• Gastrointestinal stromal tumors (GISTs): Originate in the connective tissue of the colon wall. Usually found more often in the stomach or small intestine but can occur in the colon.
• Lymphomas: Start in immune system cells, though the colon is not the most common site.
• Sarcomas: Very rare; arise in muscle, fat, or blood vessels in the colon wall.

While adenocarcinoma is by far the most frequent diagnosis, doctors always identify the exact type to guide treatment.

What Are the Causes of Colon Cancer?

The exact cause of colon cancer is not always clear. However, most cases begin with genetic mutations in colon cells that allow them to grow uncontrollably. Over time, these abnormal cells form polyps that may turn cancerous.

Contributing causes include:

• Genetic changes passed down in families.
• Chronic inflammation of the colon lining.
• Unhealthy lifestyle habits such as poor diet, smoking, or heavy alcohol use.
• Aging, since cell damage accumulates over the years.

Not every polyp will become cancer, but removing polyps early is one of the best ways to prevent colon cancer. Having risk factors does not mean you will definitely get colon cancer, but it means your chances are higher. That’s why lifestyle changes and early screening are so important.

What Are the Risk Factors for Colon Cancer?

Lifestyle Factors

• Eating a diet high in red or processed meats and low in fiber.
• Lack of regular physical activity.
• Being overweight or obese.
• Smoking and heavy alcohol consumption.

Family History and Genetics

• A family history of colon cancer or polyps increases risk.
• Inherited syndromes such as Lynch syndrome or familial adenomatous polyposis (FAP) significantly raise the likelihood of colon cancer.

Medical Conditions

• Inflammatory bowel disease (IBD), including Crohn’s disease or ulcerative colitis.
• Type 2 diabetes, which has been linked to higher risk.

Age and Ethnicity

• Risk increases significantly after age 50, although younger adults are increasingly being diagnosed.
• Certain groups, including African Americans and those of Ashkenazi Jewish descent, have a higher risk.

What Are the Symptoms of Colon Cancer?

In the early stages, colon cancer may cause few or no symptoms. That’s why screening is so important. When symptoms do appear, they may include:

Early Warning Signs

• Blood in the stool (bright red or very dark).
• Persistent changes in bowel habits, such as diarrhea, constipation, or narrow stools.
• Frequent abdominal discomfort, cramps, or bloating.
• A feeling that the bowel does not empty completely.

Advanced Symptoms

• Unexplained weight loss.
• Fatigue and weakness, often from anemia due to hidden blood loss.
• Severe abdominal pain or intestinal blockage.

If you experience any of these symptoms, it’s important to see a doctor right away.

How Is Colon Cancer Diagnosed?

Doctors use several tests to confirm whether colon cancer is present.

• Colonoscopy: The gold standard. This procedure involves inserting a thin, flexible tube with a light and camera (a colonoscope) into the rectum and through the entire colon. During a colonoscopy, doctors can not only see polyps or suspicious areas but also remove them or take small samples in the same sitting.
• Fecal occult blood test (FOBT) or fecal immunochemical test (FIT): Detects hidden blood in stool.
• CT colonography (virtual colonoscopy): Uses advanced imaging to examine the colon.
• Biopsy: During the colonoscopy, the doctor can take a small tissue sample (biopsy) of any suspicious areas. The tissue sample is then examined under a microscope in a lab to determine if the cells are cancerous and how aggressive they are.
• Blood tests: Not diagnostic but may show anemia or elevated tumor markers such as CEA (carcinoembryonic antigen).

Staging of Colon Cancer

Staging

Colon cancer is staged to describe how far it has spread:

• Stage 0: Cancer is only in the innermost layer of the colon.
• Stage I: Cancer has spread into the colon wall but not beyond it.
• Stage II: Cancer has grown through the wall but hasn’t reached lymph nodes.
• Stage III: Cancer has spread to nearby lymph nodes.
• Stage IV: Cancer has spread (metastasized) to distant organs, such as the liver or lungs.

Grading

Grading describes how abnormal the cancer cells look:

• Low-grade (well-differentiated) cancers grow more slowly.
• High-grade (poorly differentiated) cancers tend to grow and spread faster.

Staging tells us how far the cancer has spread. Grading tells us how aggressive the cancer cells look. Doctors combine these to decide on the best treatment plan for you.

What Are the Treatment Options for Colon Cancer?

Surgery: 

This is the primary treatment for many colon cancers, involving the removal of the cancerous portion of the colon. For very small cancers, this might be done during a colonoscopy.

• Polypectomy: Removing cancerous polyps during colonoscopy.
• Partial colectomy: Removing the part of the colon containing cancer, along with nearby lymph nodes.
• Laparoscopic or robotic surgery: Minimally invasive approaches with faster recovery.

Medical Treatments:

• Chemotherapy: Uses drugs to kill cancer cells. Often recommended after surgery for stage III and some stage II cancers. Common drug regimens include FOLFOX (5-FU, leucovorin, oxaliplatin) and CAPOX (capecitabine and oxaliplatin).
• Targeted Therapy: Designed to block specific cancer cell pathways. Examples: bevacizumab (Avastin) and cetuximab (Erbitux). Used mainly in advanced or metastatic colon cancer.
• Immunotherapy: Helps the body’s immune system recognize and attack cancer cells. Most effective in tumors with genetic changes such as microsatellite instability-high (MSI-H). Example: pembrolizumab (Keytruda).
• Radiation Therapy: Not commonly used in colon cancer unless the cancer has spread to nearby structures or is causing symptoms.

Proton Therapy: When Is It Applicable?

Proton therapy is a type of radiation therapy that uses protons instead of X-rays. It is more precise and may reduce damage to surrounding tissues. While it is rarely used for colon cancer, it may be considered in select cases like advanced cases, local recurrences, or when the tumor is near critical structures to reduce side effects and protect healthy tissue.

What Is the Prognosis for Colon Cancer?

The outlook for colon cancer depends on the stage at diagnosis:

• Stage I: Over 90% 5-year survival rate.
• Stage II: Around 75–85%.
• Stage III: About 50–65%.
• Stage IV: Around 15%, though newer treatments are improving outcomes.

Other factors influencing prognosis include patient age, general health, genetic features of the tumor, and response to treatment. Survival rates are averages — they don’t predict exactly what will happen in your case. Many people live long and healthy lives after treatment, especially when the cancer is caught early.

Screening and Prevention of Colon Cancer

Screening guidelines for adults at average risk:

• Begin regular screening at age 45.
• Colonoscopy every 10 years is the gold standard.
• Alternative options: annual FIT test, stool DNA test every 3 years, or CT colonography every 5 years.

Even if you feel healthy, start regular colon cancer screening at age 45. If you have a family history or other risks, your doctor may suggest earlier checks.

Prevention Tips

• Eat a diet high in fiber, fruits, and vegetables.
• Limit red and processed meats.
• Stay physically active and maintain a healthy weight.
• Avoid smoking and reduce alcohol consumption.
• Manage chronic conditions like diabetes.

For International Patients

People from around the world come to Apollo Hospitals for the treatment of colon cancer. Our international patient services team will guide you all the way from seeking the first virtual connect all the way to treatment in India and then returning home post treatment.

Services include:

• Medical opinions and scheduling
  • Pre-arrival medical review of reports and imaging.
• Travel and logistics
  • Assistance with visa invitation letters, airport transfers, and nearby accommodation options.
  • Dedicated international patient coordinators to guide through each step.
• Language and cultural support
  • Interpreter services in multiple languages.
  • Clear, simple explanations at every stage with written care plans.
• Financial coordination
  • Transparent treatment estimates and packages when possible.
  • Support with international payment methods and insurance coordination.
• Continuity of care
  • Shared records, imaging, and treatment summaries for home doctors.
  • Telemedicine follow-ups for convenience after returning home.

Frequently Asked Questions (FAQs)

1. What is the survival rate for colon cancer?

Survival rates vary by stage. Early-stage colon cancers have over 90% 5-year survival, while advanced stages have lower rates.

2. What are the treatment side effects?

Side effects depend on the treatment. Surgery can cause temporary bowel changes. Chemotherapy may cause nausea, fatigue, and hair loss. Targeted therapies can cause skin changes, and immunotherapy may trigger immune-related side effects. Not everyone experiences all side effects, and your care team will give medicines and support to make you as comfortable as possible.

3. Can colon cancer come back after treatment?

Yes, recurrence is possible, especially in advanced cases. Regular follow-up with scans and colonoscopies helps detect recurrence early.

4. How long is recovery after colon cancer surgery?

Hospital stays usually last 4–7 days. Full recovery may take 4–6 weeks, though minimally invasive surgery can shorten recovery time.

5. Is colon cancer curable?

Yes, many cases, especially when detected early, can be cured with surgery. Even advanced cases may be controlled for long periods with modern treatments.

6. What is the cost of colon cancer treatment?

Costs depend on the stage, type of treatment, and location. At Apollo, costs are significantly lower compared to the US or Europe, while maintaining international standards.

7. Is colon cancer hereditary?

About 5–10% of cases are due to inherited syndromes. If you have a family history, genetic counseling and earlier screening are recommended.