Treatment for Colon Cancer

Surgery is the most common treatment for colorectal cancer. During surgery, the tumor, a small margin of the surrounding healthy bowel, and adjacent lymph nodes are removed. The surgeon then reconnects the healthy sections of the bowel. In patients with rectal cancer, the rectum is permanently removed. The surgeon then creates an opening (colostomy) on the abdomen wall through which solid waste in the colon is excreted. Specially trained nurses (enterostomal therapists) can help patients adjust to colostomies, and most patients with colostomies return to a normal lifestyle.

The long term prognosis after surgery depends on whether the cancer has spread to other organs (metastasis). The risk of metastasis is proportional to the depth of penetration of the cancer into the bowel wall. In patients with early colon cancer which is limited to the superficial layer of the bowel wall, surgery is often the only treatment needed. These patients can experience long term survival in excess of eighty percent. In patients with advanced colon cancer, wherein the tumor has penetrated beyond the bowel wall and there is evidence of metastasis to distant organs, the five year survival rate is less than ten percent.

In some patients, there is no evidence of distant metastasis at the time of surgery, but the cancer has penetrated deeply into the colon wall, or reached adjacent lymph nodes. These patients are at risk of tumor recurrence either locally or in distant organs. Chemotherapy in these patients may delay tumor recurrence and improve survival.

Chemotherapy is the use of medications to kill cancer cells. It is a systemic therapy, meaning that the medication travels throughout the body to destroy cancer cells. After colon cancer surgery, some patients may harbor microscopic metastasis (small foci of cancer cells that cannot be detected). Chemotherapy is given shortly after surgery to destroy these microscopic cells. Chemotherapy given in this manner is called adjuvant chemotherapy. Recent studies have shown increased survival and delay of tumor recurrence in some patients treated with adjuvant chemotherapy within five weeks of surgery. Most drug regimens have included the use of 5-flourauracil (5-FU). On the other hand, chemotherapy for shrinking or controlling the growth of metastatic tumors has been disappointing. Improvement in the overall survival for patients with widespread metastasis has not been convincingly demonstrated.

Treatment depends partly on the stage of the cancer. This means how far the tumor has spread through the layers of the intestine, from the innermost lining to outside the intestinal wall and beyond:

Stage 0: Very early cancer on the innermost layer (more accurately considered a precursor to cancer)
Stage I: Tumor in the inner layers of the colon
Stage II: Tumor has spread through the muscle wall of the colon
Stage III: Tumor that has spread to the lymph nodes
Stage IV: Tumor that has spread to distant organs

Stage 0 colon cancer may be treated by cutting out the lesion, often via a colonoscopy. For stages I, II, and III cancer, more extensive surgery to remove a segment of colon containing the tumor and reattachment of the colon is necessary. (See colon resection.) This procedure only rarely requires a colostomy.

Almost all patients with stage III colon cancer, after surgery, should receive chemotherapy (adjuvant chemotherapy) with a drug known as 5-fluorouracil given for approximately 6 - 8 months. This drug has been shown to increase the chance of a cure. There is some debate as to whether patients with stage II colon cancer should receive chemotherapy after surgery, and patients should discuss this with their oncologist.

Chemotherapy is also used for patients with stage IV disease in order to shrink the tumor, lengthen life, and improve the patient's quality of life. Irinotecan, oxaloplatin, and 5-fluorouracil are the 3 most commonly used drugs, given either individually or in combination. There are oral chemotherapy drugs which are similar to 5-fluroruracil, the most commonly used being capecitabine (Xeloda).

Oxaliplatin, a newer chemotherapy drug, was approved by the FDA in 2002 and is also active against colon cancer. It is often used in combination with 5-fluorouracil, and studies are being done that combine it with other chemotherapy drugs. Other chemotherapy agents, including drugs that specifically target abnormalities in cancer cells, are currently in development and undergoing clinical trials.

For patients with stage IV disease that is localized to the liver, various treatments directed specifically at the liver can be used. Tumors may be surgically removed, burned, or frozen in some cases. Chemotherapy or radioactive substances can sometimes be infused directly into the liver.

Radiation therapy is occasionally used in patients with colon cancer, but this is often used in combination with chemotherapy for patients with stage III rectal cancer.

Sometimes different treatments are combined.

Surgery to remove the tumor is the most common treatment for colorectal cancer. Generally, the surgeon removes the tumor along with part of the healthy colon or rectum and nearby lymph nodes. In most cases, the doctor is able to reconnect the healthy portions of the colon or rectum. When the surgeon cannot reconnect the healthy portions, a temporary or permanent colostomy is necessary. Colostomy, a surgical opening stoma through the wall of the abdomen into the colon, provides a new path for waste material to leave the body. After a colostomy, the patient wears a special bag to collect body waste. Some patients need a temporary colostomy to allow the lower colon or rectum to heal after surgery. About 15 percent of colorectal cancer patients require a permanent colostomy.

Chemotherapy is the use of anticancer drugs to kill cancer cells. Chemotherapy may be given to destroy any cancerous cells that may remain in the body after surgery, to control tumor growth, or to relieve symptoms of the disease. Chemotherapy is a systemic therapy, meaning that the drugs enter the bloodstream and travel through the body. Most anticancer drugs are given by injection directly into a vein (IV) or by means of a catheter, a thin tube that is placed into a large vein and remains there as long as it is needed. Some anticancer drugs are given in the form of a pill.
Radiation therapy, also called radiotherapy, involves the use of high-energy x-rays to kill cancer cells. Radiation therapy is a local therapy, meaning that it affects the cancer cells only in the treated area. Most often it is used in patients whose cancer is in the rectum. Doctors may use radiation therapy before surgery (to shrink a tumor so that it is easier to remove) or after surgery (to destroy any cancer cells that remain in the treated area). Radiation therapy is also used to relieve symptoms. The radiation may come from a machine (external radiation) or from an implant (a small container of radioactive material) placed directly into or near the tumor (internal radiation). Some patients have both kinds of radiation therapy.
Biological therapy, also called immunotherapy, uses the body's immune system to fight cancer. The immune system finds cancer cells in the body and works to destroy them. Biological therapies are used to repair, stimulate, or enhance the immune system's natural anticancer function. Biological therapy may be given after surgery, either alone or in combination with chemotherapy or radiation treatment. Most biological treatments are given by injection into a vein (IV).
Clinical trial (research studies) to evaluate new ways to treat cancer are an appropriate option for many patients with colorectal cancer. In some studies, all patients receive the new treatment. In others, doctors compare different therapies by giving the promising new treatment to one group of patients and the usual (standard) therapy to another group.

Research has led to many advances in the treatment of colorectal cancer. Through research, doctors explore new ways to treat cancer that may be more effective than the standard therapy.

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