Know Your Options for Treating Colorectal Cancer
Treatment options and recommendations for colorectal cancer depend on several factors, including the type and stage of cancer, possible side effects, and your preferences and overall health. The following treatments are the standard of care for colorectal cancer. When making treatment plan decisions, you might also consider taking part in a clinical trial.
Surgery is the removal of the tumor and surrounding tissue during an operation. This is the most common treatment for colorectal cancer and is often called surgical resection. Part of the healthy colon or rectum and nearby lymph nodes will also be removed.
Some people may be able to have laparoscopic colorectal cancer surgery. With this technique, several viewing scopes are passed into your abdomen while you are under anesthesia. The incisions are smaller and the recovery time is often shorter than with standard colon surgery. Laparoscopic surgery is as effective as conventional colon surgery in removing the cancer.
Chemoradiation therapy is often used in rectal cancer before surgery to avoid colostomy or reduce the chance that the cancer will recur.
Less often, a person with rectal cancer may need to have a colostomy. This 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 pouch worn by the individual. 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 before surgery when needed, most people treated for rectal cancer do not need a permanent colostomy.
Many people need to retrain their bowel after surgery, which may take some time and assistance. You should talk with your doctor if you do not regain good control of bowel function.
Radiation therapy is the use of high-energy X-rays to destroy cancer cells. It is commonly used for treating rectal cancer because this tumor tends to recur near where it originally started. A radiation therapy regimen usually consists of a specific number of treatments given over a set period. Radiation treatment is usually given five days a week for several weeks and may be given in the doctor’s office or at the hospital.
External-beam radiation therapy uses a machine to deliver X-rays to where the cancer is located. For some people, 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 get rid of small areas of tumor that could not be removed during surgery. In one type of brachytherapy with a product called SIR-Spheres, tiny amounts of yttrium-90 (a radioactive substance) are injected into the liver to treat colorectal cancer that has spread to the liver when surgery is not an option. While limited information is available about how effective this approach is, some studies suggest that it may help slow the growth of cancer cells.
For rectal cancer, radiation therapy may be used before surgery to shrink the tumor so that it is easier to remove, or after surgery to destroy any remaining cancer cells, as both have worked to treat this disease. 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. One study found that radiation therapy plus chemother-apy before surgery worked better than 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 people who needed permanent colostomies, and fewer problems with scarring of the bowel in the area where the radiation therapy was given.
Chemotherapy is the use of drugs to kill cancer cells, usually by stopping the cancer cells’ ability to grow and divide. Systemic chemotherapy is delivered through the bloodstream to reach cancer cells throughout the body. A chemotherapy regimen usually consists of a specific number of cycles given over a set period. Chemotherapy for colorectal cancer is usually injected directly into a vein, although some chemotherapy can be given as a pill. You may receive one drug at a time or combinations of different drugs at the same time.
Chemotherapy may be given after surgery to eliminate any remaining cancer cells. For some people with rectal cancer, the doctor will give chemotherapy and radiation therapy before surgery to reduce the size of a rectal tumor and reduce the chance of cancer returning.
Systemic chemotherapy is delivered through the bloodstream to reach cancer cells throughout the body.
Currently, several drugs are approved by the U.S. Food and Drug Administration to treat colorectal cancer in the United States. Your doctor may recommend one or more of them at different times during treatment. These drugs include fluorouracil (5-FU, Adrucil), capecitabine (Xeloda), irinotecan (Camptosar), oxaliplatin (Eloxatin), bevacizumab (Avastin), cetuximab (Erbitux), panitumumab (Vectibix), and ziv-aflibercept (Zaltrap).
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 is a treatment that targets the cancer’s specific genes, proteins, or the tissue environment that contributes to cancer growth and survival. This type of treatment blocks the growth and spread of cancer cells while limiting damage to normal cells.
Studies show that not all tumors have the same targets. To find the most effective treatment, your doctor may run tests to identify the genes, proteins, and other factors in your tumor. As a result, doctors can better match each person with the most effective treatment whenever possible. In addition, many research studies are taking place to find out more about specific molecular targets and new treatments directed at them. These drugs are becoming more important in the treatment of colorectal cancer.
Anti-angiogenesis therapy is a type of targeted therapy. It is focused on stopping angiogenesis, which is 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. Bevacizumab is a type of anti-angiogenesis therapy called a monoclonal antibody. When given with chemotherapy, bevacizumab increases the length of time people with advanced colorectal cancer live. In 2004, the FDA approved bevacizumab along with chemotherapy for the first-line treatment of people with advanced colorectal cancer. Studies have shown it is also effective as second-line therapy along with chemotherapy. Ziv-aflibercept is another type of anti-angiogenesis therapy that is used along with FOLFIRI chemotherapy as a second-line treatment for metastatic colorectal cancer. In addition, the drug regorafenib (Stivarga) was approved in 2012 for people with metastatic colorectal cancer who have already received certain types of chemotherapy and other targeted therapies.
Epidermal Growth Factor Receptor Inhibitors
An EGFR inhibitor is another type of targeted therapy. Researchers have found that drugs that block EGFR may be effective in stopping or slowing the growth of colorectal cancer. Cetuximab and panitumumab are monoclonal antibodies that block EGFR. Cetuximab is an antibody made from mouse cells that still has some of the mouse structure. Panitumumab is made entirely from human proteins and is less likely to cause an allergic reaction than cetuximab.
Studies show that cetuximab and panitumumab do not work as well for tumors that have specific mutations to a gene called KRAS. The American Society of Clinical Oncology released a provisional clinical opinion recommending that everyone with metastatic colorectal cancer who may receive anti-EFGR therapy, such as cetuximab and panitumumab, have their tumors tested for KRAS gene mutations. If a tumor has a mutated form of the KRAS gene, ASCO recommends against the use of anti-EFGR antibody therapy. Furthermore, the FDA now recommends that both cetuximab and panitumumab only be given to people who have tumors with non-mutated, or wild type, KRAS genes.
In addition to treatment to slow, stop, or eliminate the cancer, an important part of cancer care is relieving a person’s symptoms and side effects. This approach is called palliative or supportive care, and it includes supporting an individual with his or her physical, emotional, and social needs at any stage of illness. Palliative treatments vary widely and often include medication, nutritional changes, relaxation techniques, and other therapies. You may also receive palliative treatments similar to those meant to eliminate the cancer, such as chemotherapy, surgery, and radiation therapy. Before treatment begins, talk with your healthcare team about the possible side effects of your specific treatment plan and your supportive care options. During and after treatment, be sure to tell your doctor or another healthcare team member if you are experiencing a problem so it is addressed as quickly as possible.