Understanding Colon Cancer Treatment
Colon cancer treatment may seem overwhelming, but taking some time to learn about your options will help you work with your doctor and find the right treatment. The colon cancer treatment plan that is best for you will depend on your stage of disease.
A diagnosis of cancer will lead to staging and other tests to help determine the outlook and the appropriate treatments. Treatment for colon cancer includes surgery, chemotherapy, and radiation. These treatment methods may be combined.
- Surgery is used for early-stage colorectal cancer. Usually, the tumor is removed along with part of the colon and nearby lymph nodes.
- Chemotherapy may be given after surgery to kill any remaining cancer cells. It may also be given along with radiation before surgery to reduce tumor size.
- Radiation therapy is not usually used in early-stage colon cancer, but is commonly used to treat early-stage rectal cancer. It is often combined with chemotherapy.
- Clinical trials are available for individual stages of colon cancer.
Colon Cancer Stages and Treatment Options
There are several methods for staging colon cancer. The older system, known as Dukes', categorizes four basic stages: A, B, C, and D. The newer TMN system evaluates the tumor (T), lymph node (N), and how far the cancer has spread or metastasized (M). The results of TMN are combined to determine the stage of the cancer.
Colon cancer stages and treatment options are:
- In stage 0, cancer cells are fully contained in the innermost lining (mucosa) of the colon or rectum, and have not yet invaded the wall of the colon
- Treatment for stage 0 cancer usually involves surgical removal of the polyp (polypectomy) during colonoscopy.
- In stage I, the cancer has spread through the mucosa of the colon wall into middle layers of tissue.
- Treatment for stage I involves resection of the tumor. The tumor may be removed along with part of the colon (colectomy).
- In stage IIA, the cancer has spread beyond the middle layers to the outer tissues of the colon or rectum. In stage IIB, the cancer has penetrated through the colon or rectum wall into nearby tissue or organs.
- Treatment for stage II cancer involves surgical resection. Chemotherapy after surgery (adjuvant chemotherapy) plus radiation is considered standard treatment for stage II rectal cancer, but is under debate for stage II colon cancer.
- In stage III, lymph nodes are involved but not distant sites. Stage IIIA and IIIB cancer has spread to as many as 3 lymph nodes. Stage IIIC cancer involves 4 or more lymph nodes.
- Treatment for stage III colon cancer involves surgery and adjuvant chemotherapy with the FOLFOX regimen (5-FU, leucovorin, oxaliplatin). For patients with stage III rectal cancer, treatment includes chemotherapy and radiation, either before or following surgery.
- Stage IV is metastasized cancer. The cancer has spread to nearby lymph nodes and to other organs of the body such as the liver or lungs.
- Treatment for stage IV cancer may sometimes include surgery. When cancer has spread, surgery to remove or bypass obstructions in the intestine may be performed. In these circumstances, surgery is considered palliative in that it may improve symptoms but will not lead to cure. In some cases, surgery may also be performed to remove tumors in areas that the cancer has spread, such as the liver, ovaries, or lung.
- Chemotherapy is standard treatment for metastasized cancer. In advanced colon cancer, chemotherapy is either given directly into the arteries of the liver when it is involved or intravenously (through a vein) with 5-FU and leucovorin. The targeted therapy biologic drug bevacizumab may also be added. Other alternative chemotherapy choices are capecitabine, or irinotecan combined with cetuximab. Radiation therapy may be used in place of chemotherapy or in combination with it. Studies indicate that chemotherapy offers only a modest improvement in survival, but may help reduce symptoms.
Prognosis
Colon cancer is among the most curable of cancers when it is caught in its early stages. The term "5-year survival" means that patients have lived at least 5 years since diagnosis. The 5-year survival rate for colon cancer diagnosed and treated at stage I is 93%. The rates fall to 72 - 85% for stage II, 44 - 83% for stage II, and 8% for stage IV. However, there are other factors, including the appearance of cancer cells under the microscope, that can contribute to a patient's prognosis.
Follow-Up Monitoring
Doctors recommend follow-up testing to detect recurring cancer after the completion of treatment. General guidelines include:
Physical Examination
Most colorectal cancer recurrences happen within 3 years after surgery. Patients should see their doctors for a physical examination every 3 - 6 months for the first 2 years, every 6 months through the fifth year, and at the doctor's and patient's discretion during subsequent years.
Colonoscopy
Patients should have a colonoscopy 1 year after surgery. If the results are normal, patients should then receive a colonoscopy 3 years later and then every 5 years. Patients with abnormal results or who have hereditary types of cancer may need more frequent screenings.
A flexible sigmoidoscopy is recommended every 6 months for 5 years for patients with Stage II or III rectal cancer who did not receive radiation therapy.
Carcinoembryonic Antigen Levels
Carcinoembryonic antigen (CEA) levels should be measured every 3 -6 months after surgery for 2 years in patients, and then every 6 months up to 5 years for patients with Stage II or III cancer. High CEA levels in the blood may indicate that the cancer has recurred or has spread to other parts of the body.
Imaging Tests
Patients at high risk for cancer recurrence should receive an annual computerized tomography (CT) scan of the chest, abdomen, and pelvis for the first 3 years after treatment. The CT scan can help determine if cancer has spread to the lungs or liver. Patients who have had rectal cancer, and did not have radiation therapy, should receive a pelvic CT scan. The scan is not recommended for most lower-risk patients with Stage I or II colorectal cancer. PET scans are not routinely recommended.
Other Tests
The American Society of Clinical Oncology does not recommend other follow-up blood tests such as complete blood count, liver function tests, and fecal occult blood tests. There appears to be no additional benefit for these tests.
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