If you have a blood-related cancer, such as lymphoma or some kinds of leukemia, radiation therapy may be one of your treatment options. Radiation may also be part of your treatment if you get a bone marrow or cord blood transplant.
How radiation therapy works
Radiation is a form of energy. Radiation therapy uses this energy to stop cancer cells from growing and multiplying. Radiation therapy is usually given to the patient by a machine that focuses a radiation beam on the body parts being treated. The most common machine used is called a cobalt or linear accelerator.
Radiation changes the genetic code in a cell that tells the cell how to grow and multiply. Because cancer cells are usually growing actively, radiation can stop them. When a beam of radiation enters the body, it affects cancer cells in the part of the body being treated. Any cancer cells outside that area are not affected.
However, in the area being treated, radiation also affects healthy, growing cells. Damage to the healthy cells can cause side effects. After radiation therapy is stopped, most of your body's healthy cells will grow normally again.
Uses of radiation therapy
Radiation therapy may be used to treat some leukemias and lymphomas. If your doctor recommends radiation therapy, you can ask questions about the goals of this treatment for your disease.
- For early stage Hodgkin disease (stage I-IIA), radiation therapy may be used alone to cure the disease. However, recent treatment approaches use chemotherapy together with low doses of radiation therapy.
- For advanced Hodgkin disease (stage IIB-IV), radiation therapy is rarely used. Chemotherapy is the main treatment.
- For non-Hodgkin lymphoma (NHL) that is in an early stage or is not aggressive, radiation therapy may be used either alone or with chemotherapy.
For both Hodgkin's disease and NHL, radiation may be given to what is called the mantle field. This is the area including the neck, chest and lymph nodes under the arms. Radiation may also be given to a larger area (extended field) or only to the part of the body where cancer was found and to nearby lymph nodes. The area treated and dose given depend on the patient's specific diagnosis.
For most leukemias, radiation therapy is not the main treatment. However, it may be part of the treatment plan for some patients. Cases in which it might be used include:
- To keep an acute leukemia from spreading to the central nervous system.
- To treat leukemia that returns after treatment and spreads to the brain or spinal cord.
- To relieve pain from an enlarged spleen or swollen lymph nodes for some patients with chronic lymphocytic leukemia.
- To treat disease that has spread or may spread, some patients with acute lymphocytic leukemia get radiation to the brain (cranial irradiation) and/or spine and/or testes in male patients.
Total body irradiation before bone marrow or cord blood transplant
Radiation therapy is often part of the transplant preparative regimen — treatment used to prepare a patient for a bone marrow or cord blood transplant. Total body irradiation (TBI) gives a dose of radiation to the whole body. TBI can destroy cancer cells throughout the body. It also destroys the immune system so that it will not attack the donor's cells during the transplant.
TBI can reach cancer cells within scar tissue or other areas of the body that chemotherapy may not reach. However, the dose of radiation must be low enough that the body's healthy cells can recover. For this reason, TBI alone cannot be used to destroy large numbers of cancer cells. Instead, the transplant preparative regimen uses TBI along with high-dose chemotherapy. (Some preparative regimens use only chemotherapy and do not include TBI.)
What to expect during radiation therapy
If you receive radiation therapy, your doctor will plan the radiation dose, schedule and body parts to be treated. This planning session is called a "simulation." Staff will find out how to position you so they can aim the right dose of radiation at the right place on your body. You may get small marks or tattoos on your skin. These will be used to as a guide during your treatment. The treatment does not hurt. You probably will not even feel it.
Local radiation therapy
When you get radiation therapy to treat a certain body part, you will probably be treated over several weeks. Each session may last about 20 minutes or less. During the treatment, you will remain still while a large machine aims the radiation at your body. Shields may be used to protect parts of your body that do not need treatment.
Total body irradiation
If you get total body irradiation (TBI) to help prepare for a transplant, the planning will include body measurements. These measurements are used to give the radiation evenly across your body. Sometimes shields are used to help prevent lung damage.
You will get treatments one to three times a day for two to four days. The schedule will be based on your transplant center's treatment plan (protocol) and on your diagnosis and other factors. During treatment you may be sitting or lying down. You will get treatment to one side of your body and then to the other. Each treatment session may take 30 to 60 minutes.
Radiation therapy damages healthy cells along with the cancer cells, and this damage can cause side effects. Most of the body's healthy cells recover after the therapy is stopped. The side effects you may get depend on your radiation dose and what body parts are treated. Possible side effects include:
- Tiredness (fatigue)
- Hair loss on the treated body part
- Skin irritation like a bad sunburn on the treated body part
- Nausea, vomiting or diarrhea, if the abdomen is treated
- Mouth sores, a sore throat or dry mouth, if the head or neck is treated
These side effects usually go away within a few weeks when the treatment is finished.
There can also be long-term side effects months or years after treatment. These side effects depend on your age, how much radiation you get and what body parts are treated. Possible long-term side effects include:
- Damage to the lungs or other organs
- Cataracts (caused by TBI)
- Delays in growth and the ability to learn for some children
- Risk of getting leukemia or other cancer years later (when given along with chemotherapy)
This is a basic overview of radiation therapy as a treatment that may be given to some patients with blood-related cancer. If you are offered radiation therapy, talk about the treatment with your doctor. Ask your doctor about the goals of treatment, its chances of success and the side effects you might face.