What is Radiation Therapy?
Radiation therapy, also called radiotherapy, is the use of various forms of ionizing radiation to safely and effectively treat cancer and other diseases including benign tumors.
It has been used medically since shortly after its discovery in 1895. Ionizing radiation damages the genetic code (DNA) of cells which stops them from dividing resulting in the cancer shrinking or disappearing altogether. Overall, over half of all cancer patients receive radiation therapy sometime during the course of their treatment.
Commonly, radiation therapy is given with curative intent (that is, with the hope that the treatment will cure a cancer, either by eliminating a tumor, preventing cancer recurrence, or both). In such cases, radiation therapy may be used alone or in combination with surgery or chemotherapy (treatment with anticancer drugs).
What is the goal of radiation therapy with curative intent?
When used alone, the goal of curative radiation therapy is to destroy tumors that have not spread to other parts of your body and cure you of disease.
When used in combination with chemotherapy or surgery, the goals of curative radiation therapy are to either shrink the cancer before surgery, or reduce the risk that cancer will return after you undergo surgery or chemotherapy by killing small (microscopic) amounts of cancer that might remain.
Combination of radiation therapy and surgery
Radiation therapy given before surgery is called pre-operative or neoadjuvant. Neoadjuvant radiation therapy may be given to shrink a tumor so it can be removed by surgery and be less likely to return after surgery.
Radiation therapy given during surgery is called intraoperative radiation therapy (IORT). When radiation is given during surgery, nearby normal tissues can be physically shielded from radiation exposure. Very few centers in the United States offer IORT.
Radiation therapy given after surgery is called post-operative or adjuvant radiation therapy. The purpose is to destroy any cancer cells left behind after the surgery.
Combination of radiation therapy and chemotherapy
The combination of chemotherapy and radiation therapy given at the same time is sometimes called chemo-radiation or radiochemotherapy. For some types of cancer, combining chemotherapy with radiation therapy will kill more cancer cells (increasing the likelihood of a cure), but it can also cause more side effects. Radiation therapy is typically given on a daily basis Monday through Friday; chemotherapy has many different schedules, sometimes given also daily, but sometimes once weekly or once every several weeks.
Careful monitoring of your blood counts and side effects is necessary when receiving combined chemotherapy and radiation therapy.
Radiation therapy may also be given with palliative intent. Palliative treatments are not intended to cure. Instead, they relieve symptoms and reduce the suffering to improve quality of life. The typical symptoms relieved by radiation therapy are pain, bleeding or blockage caused by a tumor.
By relieving pain a patient’s quality of life is improved with less need for narcotic medications and their potential side effects.
By stopping bleeding, a patient’s condition is improved and there is less need for transfusion.
By relieving a blockage a patient may be able to avoid a more invasive surgical procedure and also there is a reduced risk of infection caused by the blockage.