Carolyn Vachani, MSN, RN, AOCN
Ultima Vez Modificado: 28 de julio del 2002
Dear OncoLink "Ask The Experts,"
What are the standard colon cancer treatment options by stage?
Carolyn Vachani, MSN, RN, AOCN, OncoLink's Medical Correspondent, responds:
Stage I colon cancer is a tumor that has begun to invade the wall of the colon. This tumor is removed surgically and requires no further treatment. These patients should receive follow up surveillance with colonoscopy, but carcinoembryonic antigen (CEA) testing, CT scans, or x-rays are not warranted.
In Stage II & III colon cancers, the tumor has deeply invaded the bowel wall, or grown through the wall, and can involve nearby organs. In both cases, surgical removal of the tumor, a section of the bowel surrounding the tumor, and local lymph nodes for pathologic evaluation is required. The differentiation between the two stages is made by the examination of the lymph nodes. A stage II colon cancer has no cancer present in the lymph nodes, whereas a stage III colon cancer does. In addition, as part of the staging work-up, these patients should have a full colonoscopy (to look for other polyps or tumors), carcinoembryonic antigen (CEA) testing, CT scan of the abdomen and pelvis, and a chest x-ray.
The treatment of stage II colon cancer is somewhat controversial. Most studies of post-operative chemotherapy (called adjuvant chemotherapy) for stage II colon cancer have failed to show any improvement in patient survival. Despite these results, it is generally agreed that there is a subset of higher risk stage II patients who probably would benefit from adjuvant chemotherapy. High-risk patients include those who present with bowel obstruction, perforation, or tumor involvement of other organs. These patients may be eligible to participate in a clinical trial evaluating adjuvant chemotherapy in this population. In general, these patients would be treated with a regimen of 5-FU (Fluorouracil) and Leucovorin for 6 months.
The treatment of stage III colon cancer is better defined and has been validated by many studies. These patients are treated with 6 months of a 5-FU and Leucovorin regimen, of which there are several variations. The regimen may be chosen based on physician preference or the ability of the patient to tolerate the side effects of that regimen.
Radiation therapy in colon cancer has limited use. Patients who have residual tumor after surgery, invasion of another organ, or an adhesion (area where the tumor has stuck to the abdominal wall), may benefit from radiation treatments to that area.
Stage IV colon cancer has spread to other organs (liver, lung, etc). A patient may be diagnosed originally at this stage, or have progressed from stage II or III. Either way, the treatments are generally not for cure, but to improve quality of life and extend the patient's survival.
Surgery in stage IV disease varies from case to case, and is not always performed. The stage may not be discovered until after surgery has been performed, or removal of part of the colon may be done to provide relief from symptoms caused by the cancer. In some cases, it may be more important to start systemic treatment with chemotherapy, rather than performing surgery and having to allow healing time before starting treatment. In the case of progressive disease, the surgery may have occurred months to years prior.
Chemotherapy for patients who are in generally good health (also known as a good performance status) can improve quality of life and may extend survival by a few months. Chemotherapy in patients with poor a performance status has not shown much benefit, and may worsen quality of life. The standard regimen for stage IV disease in the United States is 5-FU (Fluorouracil), Leucovorin, and irinotecan (CPT-11 or Camptosar). This has been shown to be superior to 5-FU and Leucovorin alone in these patients. Studies are still evaluating the effectiveness of adding irinotecan to the regimen for stage III disease.
Two other agents, Xeloda (capecitabine) and oxaliplatin, are also being used in advanced colon cancer that has failed or is unable to tolerate standard therapy. Xeloda is an oral form of 5-FU, and may be better tolerated by patients, although it is not without side effects. Oxaliplatin is widely used in Europe, but is still in clinical trials in the United States. The trials have shown good results thus far, extending survival in patients who had failed standard therapy. The Food and Drug Administration are currently reviewing the medication for approval.