The treatment of colorectal cancer depends on the size and location of the tumor, whether the cancer has spread, and the person’s overall health. In many cases, a team of specialists, including a gastroenterologist (a doctor who specializes in the function and disorders of the gastrointestinal tract), surgeon, medical oncologist, and radiation oncologist will work with the patient to determine the best treatment plan.

This section outlines treatments that are the standard of care (the best treatments available) for this specific type of cancer. Patients are also encouraged to consider clinical trials as a treatment option when making treatment plan decisions. A clinical trial is a research study to test a new treatment to prove it is safe, effective, and possibly better than standard treatment. Your doctor can help you review all treatment options.

Overview of colorectal cancer treatment

This section provides a brief overview of the treatment of colorectal cancer by stage. Details about each treatment option follow this section.

The usual treatment of stage 0 cancer in situ is a simple polypectomy during a colonoscopy. There is no additional surgery unless the polyp is unable to be fully removed by polypectomy.

If the cancer is stage I, surgical removal of the tumor and lymph nodes is usually the only treatment.

Patients with stage II colon cancer, which involves deeper penetration of the bowel lining without involving the regional lymph nodes, are advised to talk with their doctor, as some patients are treated with adjuvant chemotherapy. This is treatment after surgery with chemotherapy aimed at trying to destroy any remaining cancer cells. However, cure rates for surgery alone are quite good, and the benefits of additional treatment are still uncertain in this setting. A clinical trial is also an option after surgery. Additional drugsare being investigated in clinical trials in combination with chemotherapy.

If the cancer is stage III and has spread to nearby lymph nodes, the treatment usually involves surgical removal of the tumor followed by adjuvant chemotherapy. A clinical trial is also an option.

For patients with stage II or III rectal cancer, radiation therapy is usually offered in combination with chemotherapy, either before or after surgery.

At stage IV, patients may or may not have surgery to remove the tumor in the colon. Standard treatment includes chemotherapy along with a targeted treatment. If possible, additional surgery to remove metastases (areas where cancer has spread) may also be done. Generally, such surgery is possible if there are a limited number of spots where the tumor has spread that are identified.

Surgery

The most common treatment for colorectal cancer is surgery to remove the tumor. Part of the healthy colon or rectum and nearby lymph nodes will also be removed. While both general surgeons and specialists may perform colorectal surgery, many people consult specialists who have additional training and experience in colorectal surgery.

Some patients may be able to undergo laparoscopic colorectal cancer surgery. With this technique, several viewing scopes are passed into the abdomen while a patient is under anesthesia. The incisions are smaller and the recovery time is often shorter than with standard colon surgery. It appears that the laparoscopic surgery is as good as conventional colon surgery in terms of its effectiveness in removing the cancer. Surgeons who perform laparoscopic surgery have been specially trained in that technique.

In a minority of cases, a person with rectal cancer may need to have a colostomy, which is a surgical opening, or stoma, through which the colon is connected to the abdominal surface to provide a pathway for waste to exit the body; such waste is collected in a bag worn by the patient. Sometimes, the colostomy is only temporary to allow the rectum to heal, but it may be permanent. With modern surgical techniques and the use of radiation therapy and chemotherapy in selected cases before surgery, most people treated for rectal cancer do not require a permanent colostomy.

The side effects of surgery include pain and tenderness in the area of the operation. The operation may also cause constipation or diarrhea, which usually goes away after a while. People who receive a colostomy may have irritation around the stoma. The doctor, nurse, or a specialist in colostomy management (called an enterostomal therapist) can teach the patient how to clean the area and prevent infection.

Many people require retraining of the bowel after surgery; this may require some time and assistance. People should talk with their doctor if they do not regain good control of bowel function. This is one of the most common side effects of those who have had a large part of the colon removed.

Radiation therapy

Radiation therapy is the use of high-energy x-rays to kill cancer cells and is commonly used in treating rectal cancer due to the tendency of this tumor to recur locally. Radiation therapy may be used before surgery (called neoadjuvant therapy) to shrink the tumor so that it is easier to remove, or after surgery to destroy any remaining cancer cells, as both have shown value in treating rectal cancer. One recent study found that pre-operative radiation therapy in combination with chemotherapy showed greater benefit compared with the same radiation therapy and chemotherapy given after surgery. The main benefits included a lower rate of the tumor coming back in the area where it started, fewer patients that needed permanent colostomies, and fewer problems with scarring of the bowel in the area where the radiation therapy was administered. Chemotherapy is often given at the same time as radiation therapy (called chemoradiation therapy) to increase the effectiveness of the radiation therapy. Chemoradiation therapy is often used in rectal cancer before surgery to avoid colostomy or reduce the chance that the cancer will recur.

External-beam radiation therapy uses a machine to deliver x-rays to the site of the body where the cancer is located. Radiation treatment is given five days a week for several weeks and may be given in the doctor's office or at the hospital.

In some cases, specialized radiation therapy techniques, such as intraoperative radiation therapy (a high, single dose of radiation therapy given during surgery) or brachytherapy (placing radioactive "seeds" inside the body), may help eliminate small areas of tumor that could not be removed during surgery.

Side effects from radiation therapy may include fatigue, mild skin reactions, upset stomach, and loose bowel movements. It may also cause bloody stools (bleeding through the rectum) or bowel obstruction. Most side effects go away soon after treatment is finished.

Sexual problems, as well as infertility (the inability to have a baby) in both men and women, may occur after radiation therapy to the pelvis and need to be addressed. Talk with your doctor for more information.

Chemotherapy

Chemotherapy is the use of drugs to kill cancer cells. Systemic chemotherapy is delivered through the bloodstream, targeting cancer cells throughout the body.

Chemotherapy may be given after surgery to eliminate any remaining cancer cells. In some situations, a doctor will give chemotherapy and radiation therapy before surgery to reduce the size of a rectal tumor and reduce the chance of cancer returning. Chemotherapy is usually injected directly into a vein, although some chemotherapy can be given as a pill.

The most common chemotherapy given for colorectal cancer may cause vomiting, nausea, diarrhea, or mouth sores. However, medications to prevent these side effects are available. Because of the way drugs are administered, these side effects are less problematic than they have been in the past for most patients. In addition, patients may be unusually tired, and there is an increased risk of infection. Neuropathy (tingling or numbness in feet or hands) may also occur. Hair loss is an uncommon side effect with the drugs used to treat colorectal cancer. There are medications to ease most side effects, including nausea, neuropathy, and diarrhea. If side effects are particularly difficult, the dose of drug may be lowered or a treatment session may be postponed. Patients should talk with their health-care team to understand when to call their doctor about side effects. These side effects usually go away once treatment is finished.

Currently, seven drugs are approved for the treatment of colorectal cancer in the United States. Your doctor may recommend one or several of them at various times during treatment. These drugs are fluorouracil (5-FU, Adrucil), capecitabine (Xeloda), irinotecan (Camptosar), oxaliplatin (Eloxatin), bevacizumab (Avastin), cetuximab (Erbitux),and panitumumab (Vectibix). (These last three are described under “Targeted therapy,” see below.) Many new drugs are in the process of being tested and may provide additional future options for treatment. Some common treatments are:

• 5-FU
  
   
• 5-FU with leucovorin (Wellcovorin), a vitamin that improves the effectiveness of 5-FU
  
   
• Capecitabine, an oral form of 5-FU
  
   
• 5-FU with leucovorin and oxaliplatin (FOLFOX)
  
   
• 5-FU with leucovorin and irinotecan (FOLFIRI)
  
   
• Irinotecan alone
  
   
• Capecitabine with either irinotecan or oxaliplatin
  
   
• Any of the above with either cetuximab or bevacizumab

The medications used to treat cancer are continually being evaluated. Talking with your doctor is often the best way to learn about the medications prescribed for you, their purpose, and their potential side effects or interactions with other medications.

Targeted therapy

Targeted therapy is a treatment that targets faulty genes or proteins that contribute to cancer growth and development. These drugs are becoming more important in the treatment of colorectal cancer.

Anti-angiogenesis therapy. Some of the first targeted treatments focused on stopping angiogenesis, the process of making new blood vessels. Because a tumor needs the nutrients found in blood vessels to grow and spread, the goal of anti-angiogenesis therapies is to “starve” the tumor. One such therapy is bevacizumab. When given with chemotherapy, bevacizumab improves survival in people with advanced colorectal cancer. In 2004, the U.S. Food and Drug Administration (FDA) approved bevacizumab along with chemotherapy for the first-line treatment of patients with advanced colorectal cancer. Recent studies have shown it also to be effective as second-line therapy along with chemotherapy. Bevacizumab is a monoclonal antibody, a substance made in the laboratory that recognizes and attaches to specific proteins on the outside of cancer cells.

Epidermal growth factor receptor (EGFR) inhibitors. Researchers have found that the EGFR protein may contribute to the growth of colorectal cancer. Cetuximab and panitumumab are monoclonal antibodies that block the EGFR. Cetuximab is an antibody made from mouse cells that still has some of the mouse structure. Panitumumab is entirely made from human proteins and is less likely to cause an allergic reaction than cetuximab. In clinical trials, a combination of cetuximab and irinotecan chemotherapy shrank tumors and slowed growth of new tumors in patients with advanced colorectal cancer. This led to the 2004 approval of cetuximab for the treatment of selected patients with advanced colorectal cancer. In clinical trials, patients who received panitumumab compared with supportive care without drug therapy had a delay in the growth of the cancer, and a small number of patients had evidence of tumor shrinkage. Research is underway to determine what role cetuximab and panitumumab might play in patients with metastatic colorectal cancer who’ve had surgery and who have not previously been given chemotherapy.

Advanced or recurrent colorectal cancer

Colorectal cancer can spread to distant organs, such as the liver, lungs, peritoneum (the tissue lining the abdomen), or a woman’s ovaries. A combination of surgery, radiation therapy, and chemotherapy can be used to slow the spread of the disease, and, in many cases, can temporarily shrink a cancerous tumor.

At this stage, surgery to remove the portion of the colon where the cancer started usually cannot cure the cancer, but it can help relieve blockage of the colon or other complications. Surgery may also be used to remove parts of other organs that contain cancer (called resection), and can cure some people if a limited amount of cancer spreads to a single organ, such as the liver or lung.

Chemotherapy and radiation therapy at this stage can rarely cure cancer, but they may help to relieve pain and other symptoms and prolong survival. Clinical trials that test new treatments may also be an option.

In colon cancer, if spread is limited to the liver and if liver resection is possible–either before or after chemotherapy–the patient has a chance of complete cure. Even in cases where cure is not possible, surgery may add months or even years to an individual’s life. Determining who can benefit from surgery in this setting is often a complicated process that involves collaboration between doctors of multiple specialties.

Treatment of recurrent cancer depends on where the cancer is located and the person’s health. Generally, the treatment options for recurrent cancer are the same as those for metastatic cancer and include surgery, radiation therapy, and chemotherapy. Clinical trials of experimental treatments may also be an option.

For more information on colorectal cancer from the American Society of Clinical Oncology, please refer to the following Patient Guides: