Radiation Therapy

Reviewed by: HU Medical Review Board | Last reviewed: August 2023

Radiation therapy is a form of cancer treatment that uses powerful, high-dose X-rays to kill lung cancer cells or stop their growth. There are multiple forms of both external and internal radiation therapy. External radiation involves pointing an X-ray beam at your lung cancer cells from a radiation machine. Internal radiation involves placing small pieces of radioactive material inside your lungs near the cancer cells. External radiation is more common.1

Radiation therapy is performed by doctors called radiation oncologists. They work with a team of other specialists to figure out the right kind of radiation for you. They also calculate the amount of radiation you need. Using no more radiation than you need helps reduce damage to your healthy cells.2

When is radiation therapy used?

Radiation therapy may be used in several situations. It is most often used:1,3

  • Along with chemotherapy to treat the cancer in multiple ways
  • Instead of surgery for those who do not want surgery or are not healthy enough to have surgery
  • Before surgery to shrink the cancer cells and make them easier to remove
  • After surgery or chemotherapy to treat any remaining cancer cells
  • To reduce the chance that cancer reaches the brain (specifically small cell lung cancer)
  • For palliative care to relieve symptoms like pain or difficulty breathing (does not cure the cancer)

External beam radiation therapy

There are many kinds of radiation therapy. External beam radiation therapy (EBRT) is a type of external radiation. It is similar to an X-ray but uses a much stronger dose. The treatments are painless and usually last only a few minutes at a time. The most common schedule for lung cancer EBRT is 5 radiation treatments per week for 5 to 7 weeks.4

There are several types of EBRT, including the following.

Stereotactic body radiation therapy (SBRT)

This is also called stereotactic ablative radiotherapy (SABR). SBRT is best for early-stage cancer when surgery cannot be done or a person does not want surgery. It uses stronger radiation but requires fewer treatments. You will also be fitted for a body frame that keeps your body still during treatments. This way, the radiation hits only a very specific area.4

3-D conformational radiation therapy (3D-CRT)

This treatment uses special computers to map out your tumors. Radiation beams are angled in different directions to hit the tumor from multiple sides. This type of radiation is less likely to damage normal tissues around the tumor.4

Intensity-modulated radiation therapy (IMRT)

This is an advanced 3D-CRT in which radiation beams match the shape of your tumor. In this kind of therapy, the strength of the beams can change throughout the treatment. IMRT is most often used when tumors are near vital organs or structures like your spinal cord.4

Stereotactic radiosurgery (SRS)

Despite its name, this procedure is not surgery. This is a kind of radiation that is done in one longer session that can last from a few minutes to a few hours. It focuses about 200 beams of radiation over the tumor using different angles. It is sometimes used for tumors that have spread to the brain. SRS can be repeated more than once if needed.4


One form of internal radiation therapy is called brachytherapy. With this technique, small pellets of radioactive material are placed in the lung near your tumors. These can be placed during surgery or during a procedure where a camera looks at your airway (bronchoscopy). These pellets are usually taken out after a short time. Permanent radioactive “seeds” that degrade over weeks may be placed, but this is less common.4

New radiation techniques

One concern with radiation is how to protect healthy tissue. Even when the radiation beams are precise, you may need to hold your breath so your lungs do not move. Experts are creating new therapies that can predict how the body moves when it breathes. With these therapies, holding your breath is not necessary.5

Radiation often has been used for those living with early-stage cancers. Radiation oncologists now understand that radiation is also effective for later-stage cancers. It can be used as an attempt to slow down these later-stage cancers from progressing.5

What are the possible side effects?

Some side effects of radiation are general, such as fatigue, nausea, or vomiting. Others affect just the site of the radiation, such as redness, peeling, or hair loss. Having a sore throat or problems swallowing is also common. These symptoms usually go away once your radiation treatment is done.4

These are not all the possible side effects of radiation therapy. Talk to your doctor about what to expect with radiation. You also should call your doctor if you have any other questions or changes that concern you about radiation.

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