Radiation therapy, sometimes called radiotherapy, involves the use of high-energy rays or particles to kill cancer cells. Radiation therapy works within cancer cells by damaging their DNA, and inhibiting their ability to grow and divide. When cancerous cells try to divide, they realize their DNA has been damaged and die instead. They are then naturally eliminated from the body. Tumors that grow rapidly, such as small cell lung cancers, will discover that their DNA has been damaged more quickly, and therefore will die more quickly. Tumors that grow more slowly, such as non-small cell lung cancers, will likewise die more slowly. Healthy cells are also affected by radiation, but can repair themselves in a way cancer cells cannot.
There are two main types of radiation therapy – external beam radiation therapy and internal beam radiation therapy (brachytherapy).
External beam radiation therapy is an effective method of delivering high-energy x-rays to the cancer. A machine called a linear accelerator focuses the radiation beam to a precise location in the body for an exact period of time. This type of radiation therapy is most often used to treat primary lung cancers or its metastasis to other organs. Each treatment lasts only a few minutes, not including setup time. Radiation treatments are typically given five days a week for several weeks.
Today, conventional external beam radiation is not used as frequently as in the past, and newer techniques are enabling doctors to more accurately treat lung cancers while minimizing exposure to nearby healthy tissue. Most doctors recommend these techniques when they are available.
Brachytherapy is most often used to shrink tumors and to relieve symptoms caused by lung cancer in an airway. This procedure is usually done through a bronchoscope, although it may also be done surgically. The doctor places a small amount of radioactive material, often in the form of pellets, either directly into the cancer or into the airway next to the cancer. Since the radiation only travels a short distance from the source, there are minimal effects on surrounding healthy tissues. In most cases, the radiation source is removed after a short time, and less often the “seeds” are left in place permanently and grow continually weaker over several weeks.
External beam radiation therapy is sometimes used as the primary treatment for lung cancer, often in combination with chemotherapy. This is particularly true if the tumor cannot be removed surgically due to its size or location, or because of the patient’s poor health status. If the patient’s tumor can be removed surgically, radiation therapy can be used either alone or in combination with chemotherapy after surgery to attempt to kill any remaining microscopic disease. Radiation therapy may also be used to relieve symptoms of advanced lung cancer.
For non-small cell lung cancer:
For small cell lung cancer:
Side effects from radiation therapy may vary from one patient to the next because the direction the beam travels through each person’s body may be different. Some people feel fine, while others are uncomfortable. Likewise, different organs respond to radiation in different ways; some may be damaged relatively quickly and side effects may appear after a short period of time, while others become damaged more slowly and the effects may not be apparent until months after treatment ends. As with any medical treatment, it is always recommended that a discussion of potential side effects is included in the doctor-patient dialogue.