Chemotherapy is the use of drugs to destroy cancer cells. Chemotherapy drugs fight cancer by interfering with the growth process of cancer cells, eventually causing the cells to die. Chemotherapy is used to shrink or eliminate the tumor, keep the tumor from spreading, destroy any cancer cells that have spread to other areas in the body, or relieve symptoms. Chemotherapy is called a systemic treatment, because it affects the entire body.
Chemotherapy is given by a medical oncologist, which is a doctor who specializes in treating cancer with medication. Some people may receive chemotherapy in their doctor’s office; others may go to the hospital. A chemotherapy regimen usually consists of a specific number of cycles given over a period of time. Some drugs are given continuously over several days; some are given several times a week.
Radiation therapy, or radiotherapy, is the use of various forms of radiation to safely and effectively treat cancer and other diseases. Radiation oncologists may use radiation to cure cancer, to control the growth of the cancer or to relieve symptoms, such as pain.
Radiation therapy works by damaging cells. Normal cells are able to repair themselves, whereas cancer cells cannot. New techniques also allow doctors to better target the radiation to protect healthy cells.
The goal of radiation therapy is to get enough radiation into the body to kill the cancer cells while preventing damage to healthy tissue. There are several ways to do this. Depending on the location, size and type of cancer, you may receive one or a combination of techniques. Your treatment team will help you to decide which treatments are best for you.
Radiation therapy can be delivered in two ways, externally and internally. During external beam radiation therapy, the radiation oncology team uses a machine to direct high-energy X-rays at the cancer. Internal radiation therapy, or brachytherapy, involves placing radioactive sources (for example, radioactive seeds) inside your body.
External Beam Radiation Therapy
During external beam radiation therapy, a beam of radiation is directed through the skin to the cancer and the immediate surrounding area in order to destroy the main tumor and any nearby cancer cells. To minimize side effects, the treatments are typically given five days a week, Monday through Friday, for a number of weeks. This allows doctors to get enough radiation into the body to kill the cancer while giving healthy cells time each day to recover.
The radiation beam is usually generated by a machine called a linear accelerator. The linear accelerator, or linac, is capable of producing high-energy X-rays and electrons for the treatment of your cancer. Using high-tech treatment planning software, your treatment team controls the size and shape of the beam, as well as how it is directed at your body, to effectively treat your tumor while sparing the surrounding normal tissue.
Several special types of external beam therapy are discussed in the next sections. These are used for specific types of cancer, and your radiation oncologist will recommend one of these treatments if he or she believes it will help you.
Intensity Modulated Radiation Therapy
Intensity modulated radiation therapy, or IMRT, is a specialized form of 3D-CRT that allows radiation to be more exactly shaped to fit the tumor. With IMRT, the radiation beam can be broken up into many “beamlets,” and the intensity of each beamlet can be adjusted individually. Using IMRT, it may be possible to further limit the amount of radiation that is received by healthy tissue near the tumor. In some situations, this may also allow a higher dose of radiation to be delivered to the tumor, potentially increasing the chance of a cure.
Brachytherapy is the placement of radioactive sources in or just next to a tumor. The word brachytherapy comes from the Greek “brachy” meaning short distance. During brachytherapy, the radioactive sources may be left in place permanently or only temporarily, depending upon your cancer. To position the sources accurately, special catheters or applicators are used.
Depending on the type of brachytherapy you received, you may need to take some precautions after you leave your treatment, particularly if you plan to be around young children or pregnant women. Ask your radiation oncologist or radiation oncology nurse about anything special you should know.
Surgery involves the removal of cancerous tissue from the body. It is the primary treatment for many types of cancer, and some cancers can be cured with surgery. Surgery can also confirm a diagnosis (biopsy), determine how far a person’s cancer has advanced (staging), relieve side effects (such as an obstruction), or ease pain (palliative surgery.)
Some types of surgery can be performed in a clinic or doctor’s office instead of the hospital. This is called outpatient surgery. Most cancer surgeries, though, will be performed in a hospital. Before surgery, consider preparing a list of questions for the surgeon. Carefully review with your doctor any preparation you may need before surgery.
Biological therapy is a type of treatment that works with your immune system. It can help fight cancer or help control side effects (how your body reacts to the drugs you are taking) from other cancer treatments like chemotherapy.
Biological therapy and chemotherapy are both treatments that fight cancer. While they may seem alike, they work in different ways. Biological therapy helps your immune system fight cancer. Chemotherapy attacks the cancer cells directly.
Several types of cancer, including some breast and prostate cancers, can only grow and spread in the presence of natural chemicals in the body called hormones. Hormone therapy fights cancer by changing the amounts of hormones in the body, and is used to treat cancers of the prostate, breast, and reproductive system. For example, tamoxifen (Nolvadex) is an anti-estrogen drug used to treat some hormone-responsive breast cancers.
Hormone therapy does have potential side effects, but most side effects go away once treatment is finished. The side effects depend on the drug and affect men and women differently.
Targeted Cancer Therapies
Targeted cancer therapies use drugs that block the growth and spread of cancer. They interfere with specific molecules involved in carcinogenesis (the process by which normal cells become cancer cells) and tumor growth. Because scientists call these molecules “molecular targets,” these therapies are sometimes called “molecular-targeted drugs,” “molecularly targeted therapies,” or other similar names. By focusing on molecular and cellular changes that are specific to cancer, targeted cancer therapies may be more effective than current treatments and less harmful to normal cells.
Advances in understanding and manipulating genes have set the stage for scientists to alter a person’s genetic material to fight or prevent disease. Gene therapy is an experimental treatment that involves introducing genetic material (DNA or RNA) into a person’s cells to fight disease. Gene therapy is being studied in clinical trials (research studies with people) for many different types of cancer and for other diseases. It is not currently available outside a clinical trial.