Colorectal Cancer

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Colorectal cancer (CRC), also known as colon cancer or rectal cancer, refers to cancer that begins in the colon or rectum, parts of the large intestine. It typically starts as polyps, which are small clumps of cells that can become cancerous over time. This disease is the third most common cancer worldwide and one of the leading causes of cancer-related deaths.

Signs & Symptoms

In the early stages of colorectal cancer, patients may not experience noticeable symptoms. As the cancer progresses, the following symptoms may develop:

  • Change in bowel habits: This includes diarrhea, constipation, or the feeling that the bowel doesn't empty completely.
  • Blood in the stool: Either visible as red blood or in the stool's appearance (dark and tarry).
  • Abdominal discomfort: Cramps, bloating, or pain in the abdomen.
  • Unexplained weight loss: Due to poor absorption of nutrients.
  • Fatigue: Often resulting from anemia due to chronic blood loss.
  • Nausea and vomiting: This can occur especially when the tumor obstructs the bowel.

If these symptoms are present, especially in individuals over 50 or with a family history of colorectal cancer, seeking medical attention promptly is crucial.

Anatomy Affected

Colorectal cancer affects the colon (the large intestine) and rectum. The colon is responsible for absorbing water and salts from food matter before it is excreted, while the rectum serves as the final part of the large intestine that stores waste material until elimination. Cancer can begin anywhere in the colon or rectum and may spread (metastasize) to nearby lymph nodes, liver, lungs, or other parts of the body.

Cause/Transmission

The exact cause of colorectal cancer is not fully understood, but several risk factors have been identified:

  1. Age: Most people diagnosed with colorectal cancer are older than 50 years. The risk increases with age.
  2. Family history: Individuals with a first-degree relative who had colorectal cancer have a higher risk.
  3. Inherited genetic mutations: Such as those associated with Lynch syndrome or Familial Adenomatous Polyposis (FAP).
  4. Diet: A diet high in red or processed meats, low in fiber, and rich in fats has been linked to a higher risk.
  5. Lifestyle factors: Smoking, excessive alcohol consumption, and physical inactivity increase the risk.
  6. Pre-existing conditions: Diseases like inflammatory bowel disease (IBD), such as ulcerative colitis or Crohn's disease, increase the risk of colorectal cancer.

Colorectal cancer is not contagious, but certain genetic mutations can be inherited, which explains the higher risk for individuals with a family history of the disease.

Treatments

Treatment for colorectal cancer depends on the stage of the disease, the location of the tumor, and the overall health of the patient. Standard treatments include:

  1. Surgery: The most common treatment for localized colorectal cancer. The goal is to remove the tumor and some surrounding healthy tissue. If the cancer has spread to lymph nodes, they may also be removed.
  2. Chemotherapy: Uses drugs to kill cancer cells or stop them from growing. Chemotherapy is often used after surgery to kill any remaining cancer cells, especially in advanced stages.
  3. Radiation therapy: Often used for rectal cancer or to shrink tumors before surgery.
  4. Targeted therapy: Drugs that target specific molecules involved in the growth of cancer cells. It is used when the cancer has spread to other areas.
  5. Immunotherapy: Uses the body’s immune system to fight cancer. This treatment is used in certain cases, especially when the cancer has high levels of microsatellite instability (MSI-H).

Prevention

While not all cases of colorectal cancer are preventable, there are several strategies that can reduce the risk:

  1. Screening: Routine screenings, such as colonoscopy, starting at age 45 or earlier for those with a family history, can detect precancerous polyps or early-stage cancer.
  2. Healthy diet: A diet high in fruits, vegetables, whole grains, and fiber can lower the risk, while reducing the intake of red and processed meats is recommended.
  3. Exercise: Regular physical activity has been shown to reduce the risk of colorectal cancer.
  4. Limiting alcohol consumption and avoiding smoking can help lower the risk of developing colorectal cancer.
  5. Weight management: Maintaining a healthy weight reduces the risk of developing many types of cancer, including colorectal cancer.

Prognosis/Outlook/Mortality Rate/Recovery Rate

The prognosis for colorectal cancer depends on the stage at which it is diagnosed and how well the treatment works. Early detection significantly improves survival rates.

  • Stage 1: Cancer is localized to the colon or rectum, with a high 5-year survival rate of about 90%.
  • Stage 2: The cancer may have spread to nearby tissues but not to lymph nodes. The survival rate drops to around 80%.
  • Stage 3: Cancer has spread to nearby lymph nodes. The 5-year survival rate is approximately 60%.
  • Stage 4: The cancer has spread to distant organs (e.g., liver or lungs). The survival rate is around 10%.

However, survival rates are continually improving with advances in treatment, especially for patients diagnosed at earlier stages. Recovery also depends on individual factors like age, overall health, and response to treatment.

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