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What is radiotherapy?
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Radiotherapy is a form of cancer treatment that may be administered alone or in combination with surgery or chemotherapy.
Also known as radiation therapy, irradiation or X-ray therapy, radiotherapy utilizes X-rays, gamma rays, electron beams and protons to attack cancer cells.
When a patient is undergoing radiotherapy treatment for cancer, the radiation makes small breaks in DNA inside of cancer cells, therefore stopping the cells from rapidly growing and in most cases causes them to die.
Some patients may be prescribed radiosensitizers, which cause cancer cells to be even more sensitive to radiotherapy.
Radiotherapy is most often delivered only to the part of the body being treated for cancer; however, sometimes normal cells are affected by radiation. Most normal cells recover and go back working as normal.
Types of radiotherapy
There are three ways in which radiotherapy is delivered — external, internal and systemic.
For external radiotherapy, special equipment directs high-energy rays into the tumor. The course of treatment for this type of radiotherapy is usually administered for weeks at a time at an outpatient center. Newer forms of external therapy that are being studied include 3-D conformal radiation therapy, intensity-modulated radiation therapy and conformal proton beam radiation therapy.
Internal radiotherapy, or brachytherapy, is when radiation is delivered via an implant placed near or inside of the tumor without harming normal cells surrounding the tumor. This type of radiotherapy allows for a higher dose of radiation delivered to a smaller area of the body compared with external radiotherapy.
The two primary types of brachytherapy are interstitial and intracavitary. Radiation is delivered via radioactive implants, including pellets, seeds, ribbons, wires, needles, capsules, balloons or tubes. With intracavitary radiotherapy, the radioactive implant is placed within a patient’s body, such as the rectum or uterus. For interstitial radiotherapy, the implant is placed either in or near the tumor.
With systemic radiotherapy, drugs that are radioactive are administered via the mouth or injected into a vein. With this delivery of radiotherapy, patients may be hospitalized for 1 to 2 days because the radiation is unsealed within the body and poses risk to others.
Benefits vs. risks
Radiotherapy affects various cancer types differently. The reasons for this is because certain cancers are more sensitive to radiotherapy and also some cancers may be located in areas of the body that are easier to treat with radiation without causing dangerous adverse events.
Although the benefit of cure outweighs the risks associated with radiotherapy, it is important to note that there are many common side effects. These include fatigue, hair loss, skin reactions, low blood counts, hair loss and difficulty eating as many experience mouth sores, nausea, vomiting and a loss of appetite. There are also possible long-term effects from radiotherapy including damage to various areas of the body and an increased risk for a different cancer type.
Also, women who are pregnant are not recommended to undergo radiotherapy as the radiation will affect the growing child. The American Cancer Society recommends women speak with their physician if there is a chance for pregnancy and inquire about birth control options. Specifically for men, it is recommended for them to avoid getting a woman pregnant while undergoing treatment with radiotherapy as the risk radiotherapy may pose to a child is not known.
Looking ahead
Research is ongoing examining the long-term effects of some of the newer external radiotherapy techniques.
Additional research is needed for conformal proton beam radiation therapy to determine if proton radiation delivers better outcomes for certain cancer types when compared with other forms of radiotherapy.
Other areas of research for radiotherapy include stereotactic body radiotherapy vs. stereotactic body proton therapy in patients with non–small cell lung cancer and standard vs. intensity-modulated pelvic radiation therapy in patients with endometrial cancer.
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