What are the treatments for colon cancer?
Surgery is the most common initial medical treatment for colorectal cancer. During surgery, the tumor, a small margin of the surrounding healthy intestine, and adjacent lymph nodes are removed. The surgeon then reconnects the healthy sections of the bowel. In patients with rectal cancer, the rectum sometimes is permanently removed if the cancer arises too low in the rectum. The surgeon then creates an opening (colostomy) on the abdominal wall through which solid waste from 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.
For early colon cancers, the recommended treatment is surgical removal. For most people with early stage colon cancer (stage I and most stage II), surgery alone is the only treatment required. However, once a colon cancer has spread to local lymph nodes (stage III), the risk of the cancer returning remains high even if all visible evidence of the cancer has been removed by the surgeon. This is due to an increased likelihood that tiny cancer cells may have escaped prior to surgery and are too small to detect at that time by blood tests, scans or even direct examination. Their presence is deduced from higher risk of recurrence of the colon cancer at a later date (relapse). Medical cancer doctors (medical oncologists) recommend additional treatments with chemotherapy in this setting to lower the risk of the cancer's return. Drugs used for chemotherapy enter the bloodstream and attack any colon cancer cells that were shed into the blood or lymphatic systems prior to the operation, attempting to kill them before they set up shop in other organs. This strategy, called adjuvant chemotherapy, has been proven to lower the risk of cancer recurrence and is recommended for all patients with stage III colon cancer who are healthy enough to undergo it, as well as for some higher risk stage II patients whose tumor may have been found to have obstructed or perforated the bowel wall prior to surgery.
There are several different options for adjuvant chemotherapy for the treatment of colon cancer. The treatments involve a combination of chemotherapy drugs given orally or into the veins. The treatments typically are given for a total of six months. It is important to meet with an oncologist who can explain adjuvant chemotherapy options as well as side effects to watch out for so that the right choice can be made for a patient as an individual.
Chemotherapy usually is given in a health care professional's clinic, in the hospital as an outpatient, or at home. Chemotherapy usually is given in cycles of treatment followed by recovery periods without treatment. Side effects of chemotherapy vary from person to person and also depend on the agents given. Modern chemotherapy agents are usually well tolerated, and side effects for most people are manageable. In general, anticancer medications destroy cells that are rapidly growing and dividing. Therefore, normal red blood cells, platelets, and white blood cells that also are growing rapidly can be affected by chemotherapy. As a result, common side effects include anemia, loss of energy, and a low resistance to infections. Cells in the hair roots and intestines also divide rapidly. Therefore, chemotherapy can cause hair loss, mouth sores, nausea, vomiting, and diarrhea, but these effects are transient.
Treatment of stage IV colorectal cancer
Once colorectal cancer has spread distant from the primary tumor site, it is described as stage IV disease. These distant tumor deposits, shed from the primary tumor, have traveled through the blood or lymphatic system, forming new tumors in other organs. At that point, colorectal cancer is no longer a local problem but is instead a systemic problem with cancer cells both visible on scan and undetectable, but likely present elsewhere throughout the body. As a result, in most cases the best treatment is chemotherapy, which is a systemic therapy. Chemotherapy in metastatic colorectal cancer has been proven to extend life and improve the quality of life. If managed well, the side effects of chemotherapy are typically far less than the side effects of uncontrolled cancer. Chemotherapy alone cannot cure metastatic colon cancer, but it can more than double life expectancy and allow for good quality of life during the time of treatment.
Chemotherapy options for colorectal cancer treatment vary depending on other health issues that an individual faces. For fitter individuals, combinations of several chemotherapeutic drugs usually are recommended, whereas for sicker people, simpler treatments may be best. Different multidrug regimens combine agents with proven activity in colorectal cancer such as 5-fluorouracil (5-FU), which is often given with the drug leucovorin (also called folinic acid) or a similar drug called levoleucovorin, which helps it work better.
Capecitabine (Xeloda), is a chemotherapy drug given in pill form. Once in the body, it is changed to 5-FU when it gets to the tumor site. Other chemotherapy drugs for colorectal cancer are irinotecan (Camptosar), oxaliplatin (Eloxatin), and trifluridine and tipiracil (Lonsurf), a combination drug in pill form. Chemotherapy regimens often have acronyms to simplify their nomenclature (such as FOLFOX, FOLFIRI, and FLOX).
Targeted therapies are newer treatments that target specific aspects of the cancer cell, which may be more important to the tumor than the surrounding tissues, offering potentially effective treatments with fewer side effects than traditional chemotherapy. Bevacizumab (Avastin), cetuximab (Erbitux), panitumumab (Vectibix), ramucirumab (Cyramza), regorafenib (Stivarga), and ziv-aflibercept (Zaltrap) are targeted therapies that have been used in the management of advanced colorectal cancer. These newer chemotherapeutic agents most often are combined with standard chemotherapy to enhance their effectiveness.
If the first treatment is not effective, second- and third-line options are available that can confer benefit to people living with colorectal cancer.
Radiation therapy in the primary treatment of colorectal cancer has been limited to treating cancer of the rectum. As noted earlier, whereas parts of the colon move freely within the abdominal cavity, the rectum is fixed in place within the pelvis. It is in intimate relationship to many other structures and the pelvis is a more confined space. For these reasons, a tumor in the rectum often is harder to remove surgically because the space is smaller and other structures can be involved with cancer. As a result, for all but the earliest rectal cancers, initial chemotherapy and radiation treatments (a local treatment to a defined area) are recommended to try and shrink the cancer, allowing for easier removal and lowering the risk of the cancer returning locally. Radiation therapy is typically given under the guidance of a radiation specialist called a radiation oncologist. Initially, individuals undergo a planning session, a complicated visit as the doctors and technicians determine exactly where to give the radiation and which structures to avoid. Chemotherapy usually is administered daily while the radiation is delivered. Side effects of radiation treatment include fatigue, temporary or permanent pelvic hair loss, and skin irritation in the treated areas.
Radiation therapy will occasionally be used as a palliative treatment to reduce pain from recurrent or metastatic colon or rectal cancer.