About Colon (Bowel) Cancer

Overview

Colon cancer is a type of tumor that starts in the colon or rectum, which are parts of the digestive system. This cancerous growth can develop from the inner wall of the large intestine. It is one of the most common types of cancer worldwide, affecting both men and women. In its early stages, colon cancer may not show obvious symptoms, making regular screenings important for early detection and treatment.

Causes and Risk Factors

Colon cancer can develop from precancerous polyps that grow in the large intestine. Some polyps may turn into malignant colon cancer if not removed early. Genetic mutations during a person's lifetime can lead to uncontrolled cell growth, contributing to colon cancer development.

• Non-modifiable risk factors for colon cancer include
  • Age over 50
  • Family history of colon cancer
  • Certain hereditary conditions that predispose individuals to colon cancer.
• Modifiable risk factors include:
  • Obesity
  • Physical inactivity
  • Diets high in salt and saturated fats
  • Smoking or exposure to secondhand smoke
  • Excessive alcohol consumption.

Symptoms

Early symptoms of colon cancer may not be noticeable, but as the disease progresses, common early signs can include:

• A change in bowel habits
• Blood in the stool or rectal bleeding
• Abdominal pain
• Fatigue
• Unexplained weight loss

In later stages as colon cancer progresses, additional symptoms may develop, such as:

• New diarrhea or constipation
• Lower abdominal pain
• Bloating
• A noticeable lump in the abdomen, often on the right side
• Inability to pass gas
• General feeling of unwellness
• Abdominal cramps
• Persistent urges to defecate despite passing stools

Diagnosis

To diagnose colon cancer, healthcare professionals may perform the following examinations, tests, and procedures:

• Medical history review: Doctors assess observable signs and symptoms, along with a family history of cancer.
• Physical exam: Healthcare providers check for tenderness, swelling, bowel sounds, and lumps.
• Blood tests: These include complete blood count, liver function tests, and tumor marker blood tests.
• Stool tests: Fecal occult blood tests or fecal immunochemical testing are conducted to detect blood in the stool.
• CT scan: This imaging test provides a 3D image of the colon, showing any abnormalities like masses or thickening that may indicate colon cancer.
• Colonoscopy: A flexible tube with a camera is inserted through the anus to view any tumors in the colon.

Additional examinations and tests may include:

• Biopsy: Doctors take a tissue sample from suspected colon tumors for a definitive diagnosis.
• Chest, pelvic, and abdominal CT scans: These imaging tests help in staging the cancer after the initial diagnosis.
• MRI scan of the liver: This technique allows doctors to assess whether cancer has spread beyond the colon.

Treatment Options

The goals of treatment for colon cancer are to cure the cancer in early stages, improve quality of life, and shrink tumors to slow their growth if a cure is not possible.

• Surgery is the main treatment for early-stage colon cancer. It involves removing the cancerous part of the colon and surrounding tissues. In some cases, a stoma (surgical opening in the abdomen) may be created.
• Chemotherapy is a systemic treatment that uses drugs to kill cancer cells or stop their growth. It can be used before or after surgery to reduce tumor size or prevent cancer from spreading.
• Radiation therapy uses high-energy rays to destroy cancer cells. It can be used alone or with surgery and chemotherapy to treat colon cancer.
• Other treatments may include targeted therapy, immunotherapy, and adjuvant chemotherapy based on the stage and characteristics of the cancer.
• Lifestyle behavior changes like maintaining a healthy weight, being physically active, and eating a balanced diet can help improve treatment outcomes and overall health.

Each of these treatments aims to remove the cancer, prevent its spread, reduce symptoms, and improve the patient's quality of life while minimizing complications.

Progression or Complications

The natural progression of colon cancer involves the growth of tumors within the colon, which can lead to complications such as obstruction, perforation, and bleeding. Tumors can block or obstruct the bowels, tear or perforate affected parts of the colon, and cause bleeding in about 50% of people with colon cancer. These complications may require urgent intervention for patients.

The impact of treatment for colon cancer is significant in reducing complications. Surgery has a cure rate of about 50%, especially when performed at an early stage. However, emergency surgeries for complications like obstruction have higher morbidity and mortality rates. Therefore, early detection and elective surgical interventions are crucial for better long-term outcomes in colon cancer treatment.