Treating Colorectal Cancer
Updated on 7/22/09
Treatment for colon cancer varies, depending on the size and location of the tumor, among other factors. Surgery is the mainstay of therapy in most cases. Sometimes chemotherapy and/or radiation therapy may be recommended as well. Each patient typically is evaluated by a team of physicians. To better understand the specific characteristics of the tumor as well as "stage" of the cancer (extent to which it has spread), the doctors order a battery of diagnostic tests, including X-rays, CT scans, and blood tests. This evaluation will help the medical team design the best and most effective treatment regimen.
This section includes information on:
Surgery
Surgery is the most common treatment for all stages of colon cancer. The surgeon may remove the cancer using one of the following procedures:
Colectomy: When the cancer is located in the colon, the surgeon performs an operation known as a colectomy to remove part of the colon. Typically, about one third of the colon is removed in the portion where the cancer resides, including the surrounding lymph nodes. This operation can be done either with an open operation through an incision (laparotomy) or using laparoscopic techniques.
Protectomy: This term is used for the surgical removal of all or part of the rectum. It is usually accomplished without a permanent colostomy. In some cases, when the cancer involves the anal sphincter, a surgeon will perform a more radical removal called an abdominoperineal resection.
The manner in which loops of the intestine are reconnected after the diseased portion is removed can vary. Some surgeons use sutures; others prefer using one of the various stapling techniques. Also, surgeons should take out lymph nodes near the colon to see if the cancer has spread. If the cancer does not appear to have invaded the lymph nodes and is completely removed during surgery, no further treatment may be needed.
When operating on rectal cancer, in the lowest part of the bowel, surgeons are using new techniques to spare surrounding tissue. Today, they often are able to leave intact nerves and sphincter muscles, preserving continence and sexual function. These innovative procedures have not only saved lives; they have greatly enhanced the quality of life for rectal cancer patients.
Protectomy with colostomy: If after resection the surgeon isn't able to reconnect the two ends of the colon, he or she may need to create a stoma, or small opening for wastes to pass through, in a procedure called a abdominoperitoneal resection, which results in a colostomy. Sometimes the colostomy is later reversed, after the intestine has had time to heal. However, if much of the lower colon is removed, the colostomy will most likely be permanent.
Surgery for metastatic disease: In some cases, even when a cancer has already spread to other organs, surgical removal (resection) of these tumor deposits can be performed. This happens when the metastases are limited in number and sites.
The liver is the most common site of metastatic disease. Liver resection has been shown to prolong survival in many cases. When not removable, other techniques such as radio-frequency ablation, microwave ablation, or cryotherapy can be used.
Staging
Once colorectal cancer is detected, your physician will perform other tests to see whether it has spread. The tumor will be assigned a "stage" depending on the extent of the disease—the further along the stage, the more serious the cancer. In most cases, staging cannot be done until the cancer is removed and analyzed. The size of the tumor alone does not indicate its stage, so pathologists will analyze how deeply into the wall of the colon it extends and whether it has spread elsewhere in the body via the lymphatic vessels and blood vessels.
In some cases, a number of different tests are used to stage colorectal cancer prior to surgery. Some, including X-rays, CAT scans, and magnetic resonance imaging (MRI), are imaging tests to get a better picture of what's going on inside the body. Your doctor may also order laboratory tests to check the components of the blood and to look for carcinoembryonic antigen (CEA), a protein that may signal the presence of cancer.
Staging of colorectal cancer
Stage 0: Tumor is limited to inside of the lining of the colon or rectum.
Stage I: Tumor has invaded several layers of the colon or rectum but has not spread outside the wall.
Stage II: Cancer has grown through the muscle wall of the colon or rectum and/or has invaded nearby tissue, but has not spread to lymph nodes.
Stage III: Cancer has spread to nearby lymph nodes, but not to other parts of the body.
Stage IV: Cancer has spread to other organs and tissues such as the liver, lung, peritoneum, or ovary.
Chemotherapy
Chemotherapy uses drugs to stop the growth of cancer cells, either by killing them or by interfering with their division and growth. This type of treatment may be given after surgery to attack cells that may have spread beyond the tumor (adjuvant therapy) or before surgery to shrink a tumor before removing it (neoadjuvant therapy). Chemotherapy is also used in cases where the cancer has spread (metastasized).
The drugs are delivered in a variety of ways. When they are taken orally or injected into a vein, they travel throughout the body. This is called systemic chemotherapy. The drugs may also be placed into an organ or body cavity to deliver a more direct blow to a tumor.
Chemotherapy is rarely given for stage 1 colorectal cancer, which is treated and often cured primarily with surgery. For stage 2 colorectal cancer, surgery is often the sole means of treatment, but some researchers think treatment with chemotherapy may give patients an extra benefit. Chemotherapy is common for advanced (stages 3 and 4) colorectal cancer; the most common chemotherapy treatments are known as FOLFOX and FOLFIRI.
Chemotherapy for colorectal cancer can be divided into two groups. Traditional cytotoxics are small chemicals, discovered long ago, that interfere with basic cell division; biologics are more recent discoveries, genetically engineered large proteins that target specific molecules. Cytotoxics include leucovorin, 5-fluorouracil (5-FU, often given with leucovorin to enhance its activity), irinotecan (Camptosar), and oxaliplatin (Eloxatin). The biologics are cetuximab (Erbitux) and panitumumab (Vectibix), both of which have the same biological target, and bevacizumab (Avastin), which targets a different growth factor.
Two commonly used chemotherapy schedules are known as FOLFOX (leucovorin, 5-FU, and oxaliplatin) and FOLFIRI (leucovorin, 5-FU, and irinote). Chemotherapy on these schedules is given at a clinic. First leucovorin and oxaliplatin or leucovorin and irinote are given as boluses (relatively rapid injections). Then the 5-FU is given through an infusion pump, which the patient stays connected to for the next 22 to 46 hours. Both FOLFOX AND FOLFIRI are given every two weeks, which means that if the patient starts the chemotherapy on a Monday, she or he will finish the infusion on Wednesday and have the next 11 days off. The infusion pump is usually disconnected at home by a home-care nurse, so only one visit to the clinic is needed. Some patients even work full time during chemotherapy!
As for the biologics, each has a specific role. Bevacizumab is approved by the Food and Drug Administration for use with whatever infusional chemotherapy is given first (FOLFOX or FOLFIRI). Side effects include impaired wound healing and bleeding or clotting, so most practitioners wait at least four weeks after major surgery to administer it. Cetuximab is approved for use after oxaliplatin and irinotecan have failed (at this point the cancer is called "chemotherapy-refractory disease").
Radiation Therapy
Radiation therapy is another treatment option for colon and rectal cancer. In radiation therapy, a machine called a linear accelerator delivers radiation, in the form of high-energy X-rays or photons, to a cancerous tumor. The radiation preferentially kills fast-growing cancer cells in the tumor. The goal is to radiate and kill as much of the tumor as possible without damaging the surrounding healthy tissues. The radiation treatment is given daily, Monday through Friday, for five to six weeks. During each radiation treatment, you lie on a flat table while the machine moves around your body and delivers the radiation. You cannot see the radiation, and it is not painful.
Radiation may be given after surgery to attack cells that may have spread beyond the tumor (adjuvant therapy) or before surgery to shrink a tumor before removing it (neoadjuvant therapy).
If the entire tumor has been surgically removed, radiation is not necessary after surgery. However, if some of the tumor is left behind or is stuck to other structures such as the bladder, then radiation is used. Sometimes chemotherapy is added to make the radiation more effective.
Delivering the radiation before surgery shrinks the tumor and decreases the chance that a permanent colostomy will be required. Recent studies also suggest that having radiation and chemotherapy before surgery works better and has fewer side effects than chemotherapy and radiation delivered after surgery.
Radiation is also used in cases where the cancer has spread to other areas in the body such as the bone and brain. This radiation decreases pain and swelling in these areas and is often given over two to three weeks.
Intraoperative radiotherapy can be given during surgery to decrease the risk that the tumor will grow back. The radiation can be delivered from outside the body, by a mobile X-ray machine, or with high-dose-rate brachytherapy. In brachytherapy, tiny radioactive beads are sent through catheters to the site where the tumor was removed. The catheters are held in place by a flexible flap made of a hard rubber.
The extent of side effects depends on several factors including individual health, location of the tumor, and amount of radiation required. Some patients have severe side effects, while others are relatively undisturbed by treatment. Side effects from radiation and chemotherapy include: weight loss, bloating, nausea, vomiting, constipation, diarrhea, fatigue, mouth sores, and skin changes. Let your doctor know about side effects you are experiencing; he or she may be able to help. A nutritionist can help you determine which foods will bother you least during treatment.
Clinical Trials
Clinical trials are research studies that are designed to test new treatments in patients. Clinical trials are used to study many types of treatment, such as new drugs or new combinations of drugs, new approaches to surgery or radiation therapy, or new methods of symptom management such as exercise or acupuncture. Clinicaltrials.gov is a comprehensive and public website on which anyone can search for ongoing clinical trials.
A clinical trial represents one of the final stages of a long and extensive research process. The search for new treatments begins in the laboratory, where scientists first develop and test new ideas. If an approach seems promising, the next step may be testing a treatment in animals to see how it affects cancer and whether it has harmful effects. However, treatments that often work well in the lab or in other animals do not always work well in people. Clinical trials are done patients to find out whether promising treatments are safe and effective in people.
Clinical trials contribute to knowledge and progress against cancer. If a new treatment proves effective in a study, it may become a new standard treatment that can help many patients. Many of today's most effective standard treatments are based on previous study results. Because of progress made through clinical trials, many people treated for cancer are now living longer.
Patients who participate in a trial receive up-to-date care from cancer experts, and either a new treatment being tested or the best available standard treatment for their cancer. They may be helped personally by the treatment they receive. If a new treatment proves effective or more effective than standard treatment, study patients who receive it may be among the first to benefit. Of course, there is no guarantee that either the new treatment being tested or the standard treatment will produce good results. New treatments also may have unknown risks.
Clinical trials include research at three different phases. Each phase answers different questions about the new treatment:
Phase 1 trials are the first step in testing a new treatment in humans. In these studies, researchers look for the best way to give a new treatment (e.g., by mouth, IV drip, or injection? how many times a day?). They also try to find out if and how the treatment can be given safely (e.g., best dose?), and they watch for any harmful side effects. Because less is known about the possible risks and benefits in Phase 1, these studies usually include only a limited number of patients, often people who have not been helped by other treatments.
Phase 2 trials focus on learning whether the new treatment has an anticancer effect (e.g., does it shrink a tumor? improve blood test results?). As in Phase 1, only a small number of people take part because of the risks and unknowns involved.
Phase 3 trials compare the results of people taking the new treatment with results of people taking standard treatment (e.g., which group has better survival rates? fewer side effects?). In most cases, studies move into Phase 3 testing only after a treatment shows promise in Phases 1 and 2. Phase 3 trials may include hundreds of people around the country. Comparing similar groups of people taking different treatments for the same type of cancer is another way to make sure that study results are significant and caused by the treatment rather than by chance or other factors. Comparing treatments with each other often shows clearly which one is more effective or has fewer side effects.
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