Expert Care for Colon Cancer

Colon cancer develops when abnormal cells grow uncontrollably in the colon—the longest part of the large intestine. It is often grouped with rectal cancer under the term colorectal cancer, although treatment planning may differ depending on the tumour’s exact location.

Many colon cancers begin as small growths called polyps. Most polyps are non-cancerous, but certain types may gradually develop into cancer. Screening can identify and remove these precancerous growths before cancer develops.

At AIROC Hospitals, Kondapur, Hyderabad, patients with suspected or confirmed colon cancer receive coordinated evaluation, personalised treatment planning and supportive care from a multidisciplinary cancer-care team.

Overview and Types

Adenocarcinoma

Adenocarcinoma develops from gland-forming cells lining the colon. It is the most common type of colon cancer.

Subtypes include:

• Conventional adenocarcinoma
• Mucinous adenocarcinoma
• Signet-ring-cell carcinoma
• Medullary carcinoma
• Serrated adenocarcinoma

Some subtypes may behave differently and require treatment based on their stage, molecular profile and pathological characteristics.

Gastrointestinal Neuroendocrine Tumours

Neuroendocrine tumours develop from specialised hormone-producing cells in the colon. They may range from slow-growing, well-differentiated tumours to aggressive neuroendocrine carcinomas.

Gastrointestinal Stromal Tumours

Gastrointestinal stromal tumours, or GISTs, develop from specialised cells within the digestive tract wall. They are uncommon in the colon and are treated differently from adenocarcinoma.

Colorectal Lymphoma

Lymphoma can occasionally begin in the lymphatic tissue of the colon. Its diagnosis and treatment differ from those of conventional colon cancer.

Colonic Sarcoma

Sarcomas are rare cancers arising from connective tissue, muscle, blood vessels or other supporting structures in the colon.

Precancerous Colon Polyps

Certain polyps may become cancerous over time. Important types include:

• Adenomatous polyps
• Sessile serrated lesions
• Traditional serrated adenomas

Hyperplastic polyps are usually considered low risk, although their size, number and location influence follow-up recommendations.

Colon cancer often begins as a polyp, and finding and removing appropriate polyps can help prevent the disease.

Symptoms and Causes

Early colon cancer may cause no noticeable symptoms. When symptoms occur, they depend on the tumour’s size and location.

Possible warning signs include:

• Blood in or on the stool
• Bright-red rectal bleeding
• Dark or black stools
• Persistent constipation or diarrhoea
• A change in stool shape or frequency
• Feeling that the bowel has not emptied completely
• Persistent abdominal pain, cramps or bloating
• Unexplained iron-deficiency anaemia
• Persistent tiredness or weakness
• Reduced appetite
• Unexplained weight loss
• Nausea or vomiting
• A lump or swelling in the abdomen

A tumour causing bowel obstruction may produce:

• Severe abdominal pain
• Increasing abdominal swelling
• Persistent vomiting
• Inability to pass stool or gas

These symptoms require urgent medical attention.

Blood in the stool, altered bowel habits, persistent abdominal discomfort, unexplained weight loss and iron-deficiency anaemia can be warning signs of colorectal cancer.

These symptoms may also occur with haemorrhoids, infections, inflammatory bowel disease and other non-cancerous conditions. However, persistent symptoms should not be ignored—even in younger adults.

What Causes Colon Cancer?

Colon cancer develops when genetic changes cause cells lining the colon to grow and divide abnormally. These changes may occur gradually, be influenced by lifestyle or environmental factors, or be inherited.

Colon cancer:

• Is not contagious
• Is not caused by touching someone with cancer
• Is not always inherited
• Can occur without a family history
• May develop in younger as well as older adults
• Cannot be diagnosed from symptoms alone

Most colon cancers arise from acquired genetic changes rather than an inherited cancer syndrome.

Diagnosis and Treatment

Diagnostic Evaluation

Evaluation for suspected colon cancer may include:

• Review of symptoms and medical history
• Family and inherited-cancer history
• Physical examination
• Abdominal examination
• Digital rectal examination when appropriate
• Complete blood count
• Liver- and kidney-function tests
• Carcinoembryonic antigen blood test
• Colonoscopy
• Biopsy during colonoscopy
• Histopathology examination
• CT scan of the chest, abdomen and pelvis
• MRI for selected clinical situations
• PET-CT when clinically appropriate
• Molecular and biomarker testing
• Genetic counselling and germline testing when indicated

Colonoscopy and Biopsy

During a colonoscopy, a flexible camera is passed through the rectum to examine the colon. The specialist can:

• Identify suspicious growths
• Remove certain polyps
• Collect tissue samples
• Assess whether a tumour is narrowing the bowel
• Examine the remaining colon for additional abnormalities

A biopsy is required to confirm most colon-cancer diagnoses.

Pathology and Biomarker Testing

The removed tissue may be tested to determine:

• Cancer type and grade
• Depth of bowel-wall invasion
• Lymph-node involvement
• Surgical-margin status
• Lymphovascular or perineural invasion
• Mismatch-repair protein status
• Microsatellite-instability status
• RAS and BRAF alterations
• HER2 status in selected cancers
• NTRK or other actionable gene changes when appropriate

These findings help determine prognosis and whether immunotherapy, targeted therapy or hereditary-cancer assessment should be considered.

Colon Cancer Staging

Colon cancer is generally classified from stage 0 to stage IV:

• Stage 0: Abnormal cells are limited to the innermost lining.
• Stage I: Cancer has grown into deeper layers of the colon wall.
• Stage II: Cancer has grown through the bowel wall but has not reached nearby lymph nodes.
• Stage III: Cancer has spread to regional lymph nodes.
• Stage IV: Cancer has spread to distant organs, commonly the liver, lungs or peritoneum.

The treatment plan depends on the stage, tumour location, molecular findings, general health and whether the cancer can be completely removed.

Treatment Options

Surgery

Surgery is the principal treatment for most localised colon cancers.

Procedures may include:

• Polyp removal during colonoscopy
• Local excision for selected very early cancers
• Partial colectomy
• Right or left hemicolectomy
• Sigmoid colectomy
• Subtotal or total colectomy
• Removal of nearby lymph nodes
• Open, laparoscopic or robotic-assisted surgery
• Surgery for selected liver, lung or peritoneal metastases

The affected portion of the colon is usually removed along with nearby lymph nodes. The healthy bowel ends may then be joined together.

A temporary or permanent stoma may occasionally be required, particularly when there is obstruction, perforation or another surgical complication.

Chemotherapy

Chemotherapy may be recommended:

• After surgery for stage III disease
• After surgery for selected high-risk stage II cancers
• Before or after surgery for selected metastatic cancers
• To reduce tumour size
• To control advanced disease
• To relieve cancer-related symptoms

The choice and duration of chemotherapy depend on the cancer stage, recurrence risk, molecular findings, previous treatments and the patient’s general health.

Targeted Therapy

Targeted medicines act on specific proteins or biological pathways involved in cancer growth.

They may be considered for selected advanced colon cancers based on:

• RAS status
• BRAF alterations
• HER2 overexpression or amplification
• NTRK gene fusions
• Other actionable molecular findings

Biomarker testing is important because a targeted treatment effective for one molecular subtype may not benefit another.

Immunotherapy

Immunotherapy may be particularly effective for selected colon cancers with:

• Mismatch-repair deficiency
• High microsatellite instability
• Certain other immune-related biomarkers

It may be used for advanced disease and, in selected clinical situations, at earlier stages based on specialist evaluation.

Radiation Therapy

Radiation therapy is not routinely used for most colon cancers because the colon moves within the abdomen. However, it may be considered in selected circumstances, such as:

• A locally advanced tumour involving nearby structures
• Incomplete surgical removal
• Cancer recurrence
• Painful bone or other metastases
• Symptom relief in advanced disease

Radiation has a more established role in rectal cancer, which is treated through a related but distinct pathway.

Treatment for Bowel Obstruction

A tumour blocking the colon may require urgent treatment, including:

• Intravenous fluids and supportive care
• Endoscopic stent placement
• Surgical tumour removal
• Bowel diversion or stoma formation

The approach depends on the obstruction’s location, severity, cancer stage and the patient’s overall condition.

Treatment of Metastatic Colon Cancer

When colon cancer has spread, treatment may involve:

• Chemotherapy
• Targeted therapy
• Immunotherapy
• Surgery for selected liver or lung metastases
• Thermal ablation
• Liver-directed treatment
• Cytoreductive surgery in carefully selected patients
• Palliative procedures to relieve obstruction, bleeding or pain

Some patients with limited metastatic disease may still be considered for treatment intended to achieve long-term disease control or potential cure.

Supportive and Rehabilitative Care

Supportive care may include:

• Pain and symptom management
• Nutritional counselling
• Management of anaemia
• Treatment of diarrhoea or constipation
• Stoma education and support
• Physiotherapy
• Psychological counselling
• Genetic counselling
• Palliative care

Treatment commonly involves surgery and may also include chemotherapy, targeted therapy, immunotherapy or other approaches depending on the cancer stage and biomarkers.

Prevention and Risk Factors

Colon cancer cannot always be prevented, but screening and healthy lifestyle measures may reduce the risk.

Possible Risk Factors

• Increasing age
• Personal history of colorectal cancer
• Previous adenomatous or serrated polyps
• Family history of colorectal cancer or advanced polyps
• Lynch syndrome
• Familial adenomatous polyposis
• MUTYH-associated polyposis
• Other inherited polyposis syndromes
• Long-standing ulcerative colitis
• Crohn’s disease involving the colon
• Overweight or obesity
• Physical inactivity
• Smoking or tobacco use
• Regular or excessive alcohol consumption
• A diet high in processed meat
• High consumption of red meat
• A diet low in fibre-rich foods
• Type 2 diabetes
• Previous abdominal or pelvic radiation in selected patients

Having one or more risk factors does not mean that a person will develop colon cancer. Some patients have no clearly identifiable risk factor.

Risk-Reduction Measures

Helpful measures include:

• Attend recommended colorectal screening
• Have precancerous polyps removed
• Maintain a healthy body weight
• Exercise regularly
• Avoid smoking and tobacco
• Limit or avoid alcohol
• Eat vegetables, fruits, whole grains and other fibre-rich foods
• Limit processed meat
• Moderate red-meat consumption
• Manage diabetes and other chronic health conditions
• Follow surveillance advice for inflammatory bowel disease
• Seek genetic counselling when there is a strong family history

Aspirin may reduce colorectal-cancer risk in some people, but it can cause bleeding and should not be started for cancer prevention without medical advice.

Colon Cancer Screening

Screening is intended for people who do not have symptoms. Anyone experiencing rectal bleeding, persistent bowel changes or unexplained anaemia requires a diagnostic evaluation rather than routine screening.

Screening options may include:

• Faecal immunochemical test
• High-sensitivity stool blood test
• Stool DNA testing
• Colonoscopy
• Flexible sigmoidoscopy
• CT colonography

An abnormal stool-based or imaging test usually requires a colonoscopy for further evaluation.

Screening can detect cancer early and identify polyps that can be removed before they become cancerous.

The appropriate starting age, test and screening interval depend on:

• National and local guidelines
• Personal and family history
• Previous polyp findings
• Inflammatory bowel disease
• Inherited genetic risk
• Previous screening results
• Overall health and life expectancy

Many international guidelines recommend that average-risk adults begin regular screening at approximately age 45, but Indian patients should discuss the appropriate schedule with their doctor based on individual risk and locally applicable guidance.

People with a strong family history, inherited syndrome, previous advanced polyps or inflammatory bowel disease may need earlier and more frequent colonoscopy.