Colorectal cancer  is a type of cancer that starts in the colon (large intestine) or rectum, which together form the lower part of the digestive tract. It is one of the most common cancers worldwide and a leading cause of cancer-related deaths, but it is often curable if detected early.

Types of Colorectal Cancer

1. Adenocarcinoma:

• The most common type, accounting for more than 90% of cases.

• Begins in the mucus-producing cells lining the colon and rectum.

2. Other Rare Types:

• Neuroendocrine Tumors: Arise from hormone-producing cells.

• Gastrointestinal Stromal Tumors (GISTs): Start in the connective tissue.

• Lymphomas: Cancers of the immune system cells in the colon.

Risk Factors

Colorectal cancer is associated with a combination of genetic, environmental, and lifestyle factors.

Non-Modifiable Risk Factors:

• Age: Most cases occur in individuals over 50.

• Family History: Having a close relative with CRC increases the risk.

• Genetic Syndromes:

• Familial Adenomatous Polyposis (FAP): Leads to hundreds of polyps and early-onset CRC.

• Lynch Syndrome: Increases the risk of CRC and other cancers.

• Personal History:

• Previous polyps or CRC.

• Inflammatory bowel diseases (IBD) like Crohn’s disease or ulcerative colitis.

Modifiable Risk Factors:

• Diet:

• High consumption of red and processed meats.

• Low fiber intake.

• Lifestyle:

• Sedentary behavior, obesity, smoking, and heavy alcohol use.

• Diabetes and Insulin Resistance:

• Increased risk in individuals with poorly controlled diabetes.

Symptoms

Early-stage colorectal cancer often has no symptoms. As the disease progresses, common symptoms may include:

• Changes in bowel habits (e.g., diarrhea, constipation, or stool narrowing).

• Blood in the stool (bright red or dark).

• Persistent abdominal pain, cramping, or bloating.

• Fatigue or weakness.

• Unintended weight loss.

• Iron-deficiency anemia.

Diagnosis

1. Screening Tests:

• Fecal Occult Blood Test (FOBT) or Fecal Immunochemical Test (FIT):

• Detects blood in the stool.

• Colonoscopy:

• Gold standard for screening; allows direct visualization of the colon and removal of polyps.

• CT Colonography:

• Virtual colonoscopy using CT imaging.

• Stool DNA Test:

• Detects genetic changes linked to CRC.

2. Diagnostic Imaging:

• CT or MRI: Used to assess tumor spread.

• PET Scan: Detects metastasis.

3. Biopsy:

• Performed during a colonoscopy to confirm diagnosis.

4. Molecular Testing:

• Identifies mutations (e.g., KRAS, NRAS, BRAF, and MSI-H) to guide treatment decisions.

Staging

Colorectal cancer is staged using the TNM system:

• Stage 0: Cancer is confined to the inner lining of the colon or rectum.

• Stage I: Tumor has invaded the wall but not reached lymph nodes.

• Stage II: Tumor extends through the wall but has not spread to lymph nodes.

• Stage III: Cancer has spread to nearby lymph nodes.

• Stage IV: Metastasis to distant organs, such as the liver or lungs.

Treatment Options

Treatment depends on the stage, location, and molecular profile of the cancer.

1. Surgery:

• Early-Stage CRC:

• Polypectomy: Removal of polyps during colonoscopy.

• Local Excision: For small tumors in the rectum.

• Advanced CRC:

• Colectomy: Removal of a portion of the colon with lymph nodes.

• Colostomy/Ileostomy: Temporary or permanent diversion of stool in some cases.

Apollo Cancer centres’ multidisciplinary approach includes:

• Minimally invasive surgical techniques
• Sphincter-preserving procedures
• Advanced reconstruction methods
• Targeted radiation therapy
• Chemotherapy protocols

Proton therapy applications for colorectal cancer is particularly beneficial for rectal cancer; proton therapy offers:

• Precise targeting of tumors
• Reduced bowel toxicity
• Better preservation of anal sphincter function
• Improved quality of life during treatment

Screening and Prevention

1. Screening Recommendations:

• Start at age 45 (earlier for high-risk individuals).

• Regular colonoscopies every 10 years for average-risk individuals.

2. Lifestyle Modifications:

• Healthy Diet: High in fiber, fruits, and vegetables; low in red/processed meats.

• Regular Exercise: Reduces risk.

• Avoid Smoking and Alcohol: Eliminating these habits lowers risk.

4. Genetic Counseling:

• For individuals with a family history or genetic syndromes.