Radiation therapy, also called radiotherapy, is the branch of medicine that deals with the treatment of cancer by delivering high-energy beams directly to a tumor, or intended target.
Radiation therapy is a common form of treatment for cancer today. According to the American Society of Radiation Oncology (ASTRO), two out of three cancer patients will receive radiation therapy either alone or in combination with other treatment approaches, such as surgery and chemotherapy. Each case is unique and your physician is the best person to decide on the suitability of radiation therapy for your treatment.
Radiation therapy has two equally important goals: to control the growth of the tumor and to do so while minimizing exposure to the surrounding normal, healthy tissue. Radiation therapy is broadly divided into external beam radiation therapy (EBRT), where radiation is delivered to the target from an external machine, and brachytherapy, where radiation is delivered by placing the radiation source inside the body near the intended target. Both techniques are used for treating a large variety of tumor types.
How Does Radiation Therapy Work ?
Radiation therapy, also known as radiotherapy, uses a focused beam of energy to damage cancerous cells while minimizing exposure to healthy tissue. Radiation damages the DNA in cancer cells, which interrupts their ability to reproduce, causing them to die and the tumor to shrink. Normal cells can recover from radiation more easily.
Treatment is delivered to the target site with a machine called a linear accelerator, or linac. The linac generates a high-energy beam, which is delivered from many different angles, to target each part of the tumor and deliver the prescribed amount of radiation. Typically, treatment is delivered five days a week over several weeks.
When designing your treatment plan, your medical team relies on one or more types of 3-D scans of your body. These can include a CT scan, an MRI, and/or a PET scan. By looking at these scans and other test results, the radiation oncologist and his or her treatment team determine which treatment technique is best suited for your particular case.
Benefits of Radiation Therapy
Radiation therapy can be used to treat many cancers, alone or in combination with other treatments. It can be used:
Possible Side Effects
With radiation therapy, serious side effects can occur. They are usually caused by damage to normal cells during the course of treatment. Side effects are typically cumulative, which means they can develop over the course of your treatment. They can be minor or severe, and depend on the size and location of the tumor, disease state, your general medical condition, and the treatment technique that is used.
Two of the most common side effects associated with radiation therapy are irritation or damage to the skin near the treatment site, and fatigue. Skin irritation may include dryness, itching, peeling, or blistering. Fatigue, for some patients, may mean feeling slightly worn out, while other patients experience severe exhaustion. Other side effects are usually specific to the type of cancer being treated, such as hair loss or sore throat when the head and neck region is treated, or urinary problems when the lower abdomen is treated. For more details about the side effects of radiation therapy, ask your radiation oncologist to explain what may occur during your particular treatment.
There are two broad categories of radiation therapy; both are designed to target the tumor precisely while minimizing exposure to the surrounding, healthy tissue. In the first category, external beam radiation therapy (EBRT), the radiation is usually delivered by a machine called a linear accelerator, or linac, which focuses a high-energy x-ray beam into your tumor site from outside your body. In the second treatment category, the radiation is delivered by radioactive material placed inside the body near the cancer cells — a procedure called brachytherapy (also called internal radiation therapy or implant radiation therapy).