Colorectal Cancer

Colorectal Cancer

Colorectal cancer is a type of cancer that begins in the colon or rectum. It is sometimes referred to as colon cancer or rectal cancer, depending on where it starts. Colorectal cancer is the third most common cancer diagnosed in both men and women in the United States.

Epidemiology

Colorectal cancer is the third leading cause of cancer-related deaths in the United States. The risk of developing colorectal cancer increases with age, with the majority of cases occurring in individuals over the age of 50. Other risk factors include a family history of colorectal cancer, certain genetic syndromes, a diet high in red or processed meats, smoking, and heavy alcohol use.

Pathophysiology

Colorectal cancer typically begins as a polyp, a small growth on the inner lining of the colon or rectum. Over time, some polyps can become cancerous. The most common type of colorectal cancer is adenocarcinoma, which originates from the glandular cells lining the colon and rectum.

Symptoms

Symptoms of colorectal cancer can vary depending on the location and size of the tumor. Common symptoms include:

• A change in bowel habits, such as diarrhea or constipation
• Blood in the stool
• Abdominal discomfort or pain
• Unexplained weight loss
• Fatigue

Diagnosis

Colorectal cancer is often diagnosed through screening tests such as colonoscopy, which allows for direct visualization and biopsy of suspicious areas. Other diagnostic tests include:

• Fecal occult blood test (FOBT)
• CT colonography
• Sigmoidoscopy

Staging

The staging of colorectal cancer is determined by the extent of the tumor, lymph node involvement, and the presence of distant metastasis. The stages range from Stage 0 (carcinoma in situ) to Stage IV (metastatic disease).

Treatment

Treatment options for colorectal cancer depend on the stage of the disease and may include:

• Surgery: The primary treatment for localized colorectal cancer, often involving resection of the affected segment of the colon or rectum.
• Chemotherapy: Used to kill cancer cells, often administered after surgery to reduce the risk of recurrence.
• Radiation therapy: Primarily used for rectal cancer, either before or after surgery.
• Targeted therapy and immunotherapy: Used in advanced cases to target specific cancer cell mechanisms.

Prevention

Preventive measures for colorectal cancer include:

• Regular screening starting at age 45 or earlier for those with a family history.
• Maintaining a healthy diet rich in fruits, vegetables, and whole grains.
• Limiting alcohol consumption and avoiding smoking.
• Regular physical activity.

Prognosis

The prognosis for colorectal cancer depends on the stage at diagnosis. Early-stage colorectal cancer has a high survival rate, while advanced-stage disease has a poorer prognosis. Regular screening and early detection are crucial for improving outcomes.

See also

• Cancer
• Gastroenterology
• Oncology

References

• American Cancer Society. "Colorectal Cancer Facts & Figures."
• National Cancer Institute. "Colorectal Cancer Treatment (PDQ®)–Patient Version."