Colorectal Cancer

Colorectal cancer, also known as bowel cancer, is a type of cancer that affects the large intestine (colon and rectum). It occurs when abnormal cells in the lining of the colon or rectum grow and multiply uncontrollably, forming a tumor.

Types of Colorectal Cancer

• Adenocarcinoma: The most common type of colorectal cancer, accounting for about 95% of cases. It arises from the glandular cells in the lining of the colon and rectum.
• Squamous cell carcinoma: A rare type of colorectal cancer that arises from the squamous cells in the lining of the anus.
• Carcinoid tumors: A rare type of tumor that arises from the hormone-producing cells in the colon and rectum.
• Gastrointestinal stromal tumors (GISTs): A rare type of tumor that arises from the connective tissue in the colon and rectum.

Risk Factors

• Age: The risk of developing colorectal cancer increases with age, with most cases occurring in people over 50 years old.
• Family history: Having a family history of colorectal cancer or certain genetic syndromes (e.g., familial adenomatous polyposis, Lynch syndrome) increases the risk.
• Diet: A diet high in red and processed meat, low in fiber, and high in fat may increase the risk.
• Obesity: Being overweight or obese increases the risk of developing colorectal cancer.
• Physical inactivity: A sedentary lifestyle may increase the risk.
• Smoking: Smoking tobacco products increases the risk of developing colorectal cancer.
• Previous radiation therapy: Having previous radiation therapy to the abdomen or pelvis may increase the risk.

Symptoms

• Blood in the stool: The most common symptom, which can be visible or occult (hidden).
• Changes in bowel habits: Diarrhea, constipation, or narrowing of the stool.
• Abdominal pain or cramping: Pain or discomfort in the abdomen, which may worsen over time.
• Weakness or fatigue: Feeling weak or tired due to anemia from blood loss.
• Unexplained weight loss: Losing weight without trying, which can be a sign of advanced disease.

Diagnosis

Colorectal cancer is typically diagnosed using a combination of the following tests:

• Fecal occult blood test (FOBT): A test that detects hidden blood in the stool.
• Flexible sigmoidoscopy: A procedure that uses a flexible tube with a camera to visualize the rectum and lower colon.
• Colonoscopy: A procedure that uses a flexible tube with a camera to visualize the entire colon.
• Biopsy: A procedure that removes a sample of tissue from the tumor for examination under a microscope.
• Imaging tests: Such as CT scans, MRI scans, or PET scans to evaluate the extent of the disease.

Treatment

The treatment of colorectal cancer depends on the stage and location of the tumor. Common treatments include:

• Surgery: To remove the tumor and affected portion of the colon or rectum.
• Chemotherapy: To kill cancer cells that have spread to other parts of the body.
• Radiation therapy: To shrink tumors before surgery or to relieve symptoms in advanced disease.
• (Targeted therapy): To target specific molecules involved in the growth and spread of cancer cells.
• Immunotherapy: To stimulate the immune system to attack cancer cells.

Stages of Colorectal Cancer

The stages of colorectal cancer are:

• Stage 0: The cancer is limited to the lining of the colon or rectum and has not invaded deeper tissues.
• Stage I: The cancer has grown into the tissue beneath the lining but has not spread to nearby lymph nodes.
• Stage II: The cancer has grown through the wall of the colon or rectum and may have invaded nearby tissues, but has not spread to nearby lymph nodes.
• Stage III: The cancer has spread to nearby lymph nodes but has not spread to distant parts of the body.
• Stage IV: The cancer has spread to distant parts of the body, such as the liver or lungs.

Prevention and Screening

Colorectal cancer can be prevented and detected early through:

• Regular screening tests: Such as FOBT, flexible sigmoidoscopy, and colonoscopy.
• Healthy diet and lifestyle: Eating a balanced diet, exercising regularly, and maintaining a healthy weight.
• Avoiding tobacco products: Quitting smoking and avoiding secondhand smoke.
• Genetic testing: For individuals with a family history of colorectal cancer or certain genetic syndromes.