What is radiation therapy?

Radiation therapy is a treatment for cancer that uses radiation to kill cancer cells and shrink tumors. Cancer occurs when old or damaged cells divide and multiply uncontrollably. Cancer cells rapidly reproduce even when your body signals them to stop. The goal of radiation therapy is to cure cancer, control cancer, or relieve cancer symptoms.Radiation kills your normal cells as well as cancer cells. Your doctor and care team will use specialized equipment and techniques to precisely target your tumor and minimize damage to healthy cells.

Radiation therapy is only one method to treat cancer and other conditions. Discuss all the treatment options with your doctor to understand which treatments are right for you.

Types of radiation therapy

The types of radiation therapy include:

  • External beam radiation therapy delivers radiation from a machine outside the body to treat many types of cancer. A radiation oncologist or technician directs the radiation beam precisely at the tumor or cancer. Stereotactic radiosurgery (Gamma Knife and CyberKnife) and proton therapy are specialized types of external beam radiation therapy.
  • Internal radiation therapy or brachytherapy involves placing radioactive material inside a tumor or right next to the tumor or cancer. For example, a radiation oncologist places radioactive seed implants at the prostate gland to treat prostate cancer.
  • Radiopharmaceuticals are radioactive medications. They are given through an IV, in pill form, or are placed in a body cavity. For example, a radiation oncologist uses radioactive iodine to treat thyroid cancer and radioactive antibodies to treat certain cases of non-Hodgkin lymphoma. Radiopharmaceuticals can also treat certain brain tumors and bone pain from bone cancer.

Other procedures that may be performed

Your doctor may recommend one or more procedures in addition to radiation therapy to treat cancer. These include:

  • Biological therapy or immunotherapy boosts or stimulates your body’s immune system to help fight cancer. 
  • Chemotherapy treats cancer with medications that slow or stop the growth of cancer cells.
  • Hormonal therapy blocks the effects of hormones that stimulate growth of certain cancers.
  • Laser therapy removes tumors and treats cancer symptoms with a laser.
  • Photodynamic therapy combines special light-sensitive drugs with specific wavelengths of light. Your doctor injects the drug into your tumor and exposes it to the light. This produces a reaction that kills cancer cells.
  • Surgery removes cancerous and noncancerous tumors. Your doctor may also use surgery to prevent cancer by removing pre-cancerous tissues.

Why is radiation therapy performed? 

Doctors use radiation therapy most often to treat cancer. Your doctor may recommend radiation therapy to: 

  • Destroy a cancerous tumor
  • Lower the risk that cancer will grow again after other treatments such as surgery or chemotherapy
  • Shrink a tumor before surgically removing it 
  • Shrink a tumor to ease pain or other cancer symptoms

Your doctor may recommend radiation therapy to treat:

  • Anal and rectal cancer
  • Bladder cancer
  • Bone cancer
  • Brain cancer and tumors
  • Breast cancer
  • Cervical, ovarian and uterine cancer
  • Head and neck cancer
  • Lung cancer
  • Lymphoma
  • Prostate cancer
  • Skin cancer

Doctors sometimes recommend a special type of radiation therapy, called stereotactic radiosurgery (Gamma Knife and CyberKnife). This is used to treat certain noncancerous brain diseases, including epilepsy, arteriovenous malformations, Parkinson’s disease, and trigeminal neuralgia.

Doctors also use radiation therapy to treat hyperthyroidism (overactive thyroid).

Who performs radiation therapy?

A radiation oncologist or an oncologist performs radiation therapy. Radiation oncologists specialize in treating cancer and related diseases with radiation. Oncologists specialize in diagnosing, treating and preventing cancer. 

How is radiation therapy performed?

Your radiation therapy will be performed in a hospital radiology department or an outpatient radiology setting. Radiation therapies vary depending on the type, size and location of the cancerous tumor, and other factors.