Radiation Therapy for Lung Cancer

January 24, 2025

This page was reviewed under our medical and editorial policy by Arya Amini, M.D., associate professor, Department of Radiation Oncology, City of Hope^® Cancer Center Duarte

Radiation therapy, also called radiotherapy, is one of the most widely used treatments for lung cancer. It may be used on its own or combined with other treatments, such as surgery or systemic therapy (such as chemotherapy, immunotherapy and targeted therapies).

Many lung cancer patients have radiation therapy treatments to help destroy the tumor, especially when surgery is not an option. It is often used in early-stage cancer or when the cancer has spread to nearby lymph nodes.

Radiation may also be used to treat limited metastatic lung cancer, where sites outside of the lung and lymph nodes can also be targeted to help improve outcomes.

Additionally, for more advanced metastatic disease, radiation therapy may be used to ease lung cancer symptoms and improve quality of life. Radiation therapy may also be used to target brain metastases, a common location for lung cancer to spread.

What Is Radiation for Lung Cancer?

Radiation therapy uses high-energy X-rays to destroy cancer cells. It works by damaging the DNA inside these cells, preventing them from growing and dividing. Over time, the body naturally gets rid of the damaged cells. Doctors may recommend radiation therapy to treat lung cancer, reduce pain or relieve other symptoms caused by the cancer.

Two main types of radiation therapy may be used to treat lung cancer.

External beam radiation therapy: This treatment uses high-energy beams aimed at the cancer from outside the body. EBRT can be delivered by high-energy X-rays called photons or heavy particle called protons.

Brachytherapy, or internal radiation: This places the radiation source directly inside or near the tumor.

Doctors called radiation oncologists carefully plan each treatment to focus on the cancer while minimizing harm to surrounding healthy tissue.

External Beam Radiation Therapy (EBRT)

External beam radiation therapy (EBRT) is the most common type of radiation therapy used to treat both small cell and non-small cell lung cancer. It directs high-energy radiation from a machine outside the body to target cancer cells in the lungs.

The treatment is painless and similar to getting an X-ray, but the radiation dose is much stronger than an X-ray imaging test. Each session lasts from five to 10 minutes. Radiation is often delivered with conventional fractionation for locally advanced non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), which is typically given five days a week for three to seven weeks, though this may vary. EBRT may also be delivered in a shorter course, referred to as stereotactic body radiation therapy (SBRT).

Newer techniques help the care team focus the radiation more precisely, reducing the risk of damage to nearby healthy tissues while appropriately targeting the cancer.

Biology-Guided Radiation Therapy (BgRT)

BgRT, also referred to as SCINTIX, is a type of radiation therapy that uses a signal created by positron emission tomography (PET) to guide the EBRT radiation in real time. PET imaging lights up active cancer and provides a real time tumor target map to pinpoint multiple areas of disease while the patient is undergoing radiation. By utilizing live data throughout the treatment session, BgRT allows the care team to more precisely target tumors.

Biology-guided radiation therapy may be used to treat early stage lung cancer or lung cancer that has metastasized to other body areas. BgRT is often referred to using the brand name of the device that delivers it, RefleXion^®.

Stereotactic Body Radiation Therapy (SBRT)

SBRT, also called stereotactic ablative body radiotherapy (SABR), is often used to treat early-stage lung cancers when surgery is not possible or desired. It may also be used for tumors that have spread to other areas, like the brain or adrenal glands. In addition to being used for primary lung cancer, SABR may also be used for cancers that spread to the lung or other body parts.

Unlike traditional radiation, SBRT delivers highly focused beams of radiation in one to five treatments instead of over several weeks. The radiation is aimed from different angles to target the tumor precisely.

Patients are positioned in a special frame to reduce lung movement during breathing, allowing the radiation to directly target the cancer.

Imaging, such as a computed tomography (CT) scan, may be performed before or during each treatment to confirm that the machine is lined up properly. Treatments vary from one to five sessions total, with each session typically lasting between 10 and 30 minutes.

3D Conformal Radiation Therapy (3D-CRT)

3D conformal radiation therapy (3D-CRT) uses computer technology to plan the radiation treatment by mapping out the tumor. This method allows the care team to deliver radiation from several angles, shaping the beams to match the tumor’s size and location. The treatment focuses on the tumor while reducing the risk of damage to healthy tissues nearby.

3D-CRT may be used for lung cancer patients who are seeking supportive or palliative care, such as for pain management or in emergencies. It is not typically used as a curative treatment for lung cancer.

Intensity-Modulated Radiation Therapy (IMRT)

Intensity-modulated radiation therapy (IMRT) is a more advanced form of 3D radiation therapy that enables doctors to precisely control the strength of the radiation beams.

Like 3D-CRT, the beams are shaped and aimed at the tumor from different angles, but IMRT also adjusts the intensity of each beam to match the tumor’s shape. This means the care team may focus higher doses of radiation on the tumor while limiting the impact to nearby healthy tissues. Because it is so precise, IMRT may have fewer side effects compared to other forms of radiation therapy, although the treatment sessions may take a bit longer.

4D Conformal Radiation Therapy (4DCT)

4D conformal radiation therapy (4DCT) is a technique that tracks the tumor’s movement as the patient breathes using imaging. Unlike standard CT scans, which capture a static image, a 4DCT shows how the tumor moves during each part of the breathing cycle. This helps doctors plan radiation therapy treatments more accurately by adjusting for lung movement.

This type of imaging may also show whether a tumor is attached to important structures in the chest, which may affect the feasibility of performing surgery on the tumor.

Stereotactic Radiosurgery (SRS)

Stereotactic radiosurgery (SRS) is a precise form of radiation therapy sometimes used to treat lung cancer that has spread to the central nervous system, including the brain and spinal canal. Even though it is called surgery, no cutting is involved. Instead, SRS delivers a high radiation dose that targets the tumor from multiple angles.

This focused approach damages the cancer cells’ DNA and may stop them from growing or spreading. SRS is often used when surgery is not an option or when the tumor is in a difficult-to-reach area.

Intraoperative Radiation Therapy (IORT)

Intraoperative radiation therapy (IORT) is a type of radiation given during surgery while the patient is asleep under anesthesia. It targets the tumor directly and allows doctors to deliver a large dose of radiation while using special shields to protect nearby healthy tissue.

IORT may be used when surgeons are unable to entirely remove the tumor or if there is a high chance the cancer will return in the same area, though it’s not commonly used to treat lung cancer.

Brachytherapy or Internal Radiation

Brachytherapy, also known as internal radiation, was commonly used in the past to treat NSCLC to help shrink tumors in the airway and relieve symptoms. Currently, EBRT is the preferred radiation therapy method for lung tumors, and brachytherapy isn’t typically used as a lung cancer treatment.

During the procedure, a doctor places a tiny radioactive source directly into the cancer or next to it. This is usually performed with a bronchoscope (a small, flexible instrument with a light and a camera), but it may also be done during surgery. The radiation only travels a short distance, mainly affecting the cancer cells while sparing nearby healthy tissue.

Patients may need to stay in the hospital for a short time during the treatment and limit visitors, especially children and pregnant women. In most cases, the radiation source is removed after a short time.

Proton Therapy

Proton therapy is a type of radiation treatment that uses protons, particles with a positive charge, to target cancer cells. It is different from traditional radiation (which uses X-rays) because protons deliver most of their energy directly to the tumor, with very little radiation affecting the surrounding healthy tissue. This allows doctors to give higher doses of radiation to the cancer while reducing the potential side effects.

Proton therapy is typically used when the cancer is near vital organs or in the reirradiation setting (when the same area is receiving a second round of radiation). The treatment is performed on an outpatient basis, with sessions lasting about 15 to 30 minutes, including setup time. Patients usually receive treatments five days a week for two to eight weeks, depending on their specific cancer.

Radiation Therapy for Non-Small Cell Lung Cancer

Radiation therapy plays a significant role in treating non-small cell lung cancer. However, the approach varies depending on the stage of the cancer. For early-stage NSCLC, radiation therapy, such as SBRT/SABR, is often used when surgery is not an option. SBRT delivers high doses of radiation in just a few sessions and is successful in targeting small tumors.

Brachytherapy, or internal radiation, may be used to shrink tumors in the airway to relieve symptoms. Proton therapy, which potentially targets tumors more precisely, may be considered for more advanced NSCLC or in the setting of repeat radiation. Research comparing proton therapy to the current standard photon therapy is ongoing.

In more advanced cancer, other forms of external beam radiation therapy (EBRT) are commonly used, such as 3D-CRT or IMRT. Radiation therapy may be given before surgery to shrink tumors or after surgery to help eliminate any remaining cancer cells. It may also be offered in the curative setting for unresectable stage 1, 2 or 3 lung cancer.

EBRT is also used for lung cancer that has spread to other organs, such as the brain, and may be given after chemotherapy to help control advanced lung cancer and try to prevent it from spreading. Each of these therapies is tailored to the patient’s condition and may be combined with other treatments to improve outcomes.

Radiation Therapy for Small Cell Lung Cancer

Radiation therapy is also a key treatment for small cell lung cancer and is often used alongside chemotherapy. In limited-stage SCLC, radiation therapy is used to target the tumor and nearby lymph nodes, usually at the same time as lung cancer chemotherapy. This is called concurrent chemoradiation. For advanced SCLC, radiation therapy may be given after chemotherapy to help control the disease and try to prevent it from spreading.

Another type of radiation therapy used in SCLC is prophylactic cranial irradiation (PCI), which helps lower the risk of cancer spreading to the brain. It is commonly used for patients with limited-stage SCLC and sometimes for advanced cancers. Patients should meet with a radiation oncologist to discuss the pros and cons of PCI.

In cases where SCLC has caused symptoms, like pain or breathing difficulties, radiation may help shrink the tumors and provide relief. This is called palliative radiation.

The most common type of radiation used for SCLC is EBRT, which directs high-energy beams at the tumor. Techniques like 3D-CRT and IMRT allow doctors to target the tumor more precisely, minimizing damage to healthy tissue.

Side Effects

Radiation therapy for lung cancer may cause side effects, but not every patient will experience them the same way. The type of radiation, the length of treatment and whether it is combined with other therapies all affect how the body reacts. Side effects of radiation therapy typically affect only the area being treated and vary in severity. Some effects appear during treatment, while others may not develop until months or years later.

Some of the most common side effects of any type of radiation therapy may include the following.

Fatigue: Many patients experience tiredness, especially after a few weeks of treatment.

Skin irritation: The treated area may become red, itchy, dry or sensitive.

Hair loss: Radiation may cause hair loss in the treated area, like on the chest. This may be temporary or permanent.

Loss of appetite: Some patients might experience reduced appetite during treatment, which may lead to weight loss.

Side effects that are specific to radiation treatment for lung cancer may include the following.

Esophagitis: Radiation to the chest may cause inflammation of the tube that carries food from the mouth to the stomach (esophagus), leading to difficulty swallowing. This inflammation may be severe, but it usually improves after treatment ends.

Radiation pneumonitis: A few months after treatment, some patients develop lung inflammation, which causes cough, shortness of breath and fever. This condition may require medication.

Fibrosis: Over months to years, inflammation from radiation pneumonitis may cause scarring of lung tissue (fibrosis), leading to breathing difficulties.

The care team at City of Hope is able to offer strategies to manage these side effects, so it is important for patients to communicate any symptoms during and after treatment.