The American Cancer Society indicates that colon cancer is the third most diagnosed cancer in the United States. Death rates related to colon cancer have dropped steadily over the past 20 years, yet the annual number of such deaths in the United States still hovers around 50,000. Improved screening procedures have led to earlier diagnoses, but some cases go undetected until an advanced stage. Stage IV is the most advanced stage of colon cancer and is also known as metastatic colon cancer.
Risk Factors
Stage IV colon cancer involves the penetration through layers of the colon and the spread to remote organs. Colon cancer often begins as a benign tumor called a polyp, which originates in the innermost layer of the colon. Some polyps are not precancerous, but if untreated, adenomatous polyps possess the ability to become cancerous. A personal or family history of colorectal polyps is therefore a significant risk factor. Lifestyle risk factors include a high-fat/low-fiber diet, excessive alcohol consumption, sedentary lifestyle, an age of 50 or over, and smoking, notes Healthcommunities.com.
Symptoms
Since colon cancers are usually slow growing, some cases may remain asymptomatic until stage IV. Common symptoms include an ongoing change in bowel movements, such as constipation, diarrhea, or narrow or ribbon-like stools. Stools may become dark or bloody. In some cases, however, the growing cancer causes occult bleeding, which is visually undetectable. Sudden weight loss, general fatigue or weakness and abdominal discomfort are also warning signs.
Diagnosis
Diagnostic methods for colon cancer include blood tests to check for elevated tumor markers in the blood, colonoscopy and biopsy of suspicious tissue, MRI, ultrasound and CT scan, according to the American Cancer Society. Routine screening procedures are crucial due to the fact that colon cancer is often diagnosed only after the patient has developed symptoms. Stage IV colon cancer may be diagnosed for the first time or may be diagnosed as a recurring cancer that was treated at an earlier stage.
Staging
Colon cancer is staged by the extent it has grown beyond the intestinal wall. Stages range from 0 to IV. The current staging system for colon cancer is known as TNM. The T refers to spread beyond the intestinal walls and the N refers to lymph node involvement. The M pertains to metastasis, or spread, to distant organs. Stage IV is only concerned with the M designation. This stage is sometimes subdivided into IVA, in which there is spread to one distant organ, and stage IVB, in which two or more distant organs are affected. The liver and lungs are the most commonly involved metastatic sites, reports the American Cancer Society.
Treatment
Treatment choices for metastatic colon cancer depend on factors such as location of the metastasis and general patient health. Since stage IV colon cancer often develops as a recurring cancer, the originating tumor might already have been surgically treated. Treatment options may include surgery on the metastatic growths plus a combination of chemotherapy and radiation to shrink and destroy the cancer, indicates the National Comprehensive Cancer Network. Targeted therapy such as monoclonal antibodies, proteins which affect properties within the cancer cells alone, may also be considered.
Survival Rates
Five-year survival rates refer to the percentage of patients that are still alive five or more years after diagnosis. Survival rates decrease dramatically at higher stages, though some stage IV colon cancers are successfully treated. The American Cancer Society reflects a five-year survival rate of 6 percent for stage IV cases of colon cancer.
References
- Healthcommunities.com: Cause and Risk Factors for Colorectal Cancer
- American Cancer Society: How Is Colorectal Cancer Staged?
- National Comprehensive Cancer Network: Colon and Rectal Cancer - Stage IV
- National Cancer Institute: Treatment Options for Colon Cancer
- American Cancer Society: What Are the Survival Rates for Colorectal Cancer by Stage?
