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Tumor Treating Fields (TTFields)
Tumor treating fields (also known as TTFields) are a type of cancer therapy that use low-energy electrical fields to disrupt cancer cells’ ability to grow and divide. TTFields may also be called alternating electric fields.
How are TTFields used to treat tumors?
TTFields are delivered through a special portable device with electrodes that are placed on your skin near the tumor. These electrodes are connected to a portable battery that you can carry in a backpack. The device sends mild electrical currents that target cancer cells while sparing most nearby healthy cells. The TTFields device usually needs to be worn for at least 18 hours each day, but people can continue most of their daily activities while wearing it.
TTFields may be used alone or along with other treatments, such as chemo or immunotherapy. TTFields tend to have few side effects (see below), so they may be used if other treatments have already been tried.
Two tumor treating fields devices are FDA-approved to treat cancer:
- Optune Gio is approved for new or recurrent glioblastoma (GBM)
- Optune Lua is approved for pleural mesothelioma that can’t be removed with surgery, as well as for metastatic non-small cell lung cancer that's grown during or after treatment with chemo.
Research studies are also looking at using TTFields for other types of cancers, such as pancreatic cancer.
Do TTFields use radiation?
TTFields do use radiation, but it’s a different type of radiation than traditional radiation therapy. The electrical fields created in TTFields are a type of non-ionizing radiation. Other types of non-ionizing radiation include radio waves, microwaves, and visible and infrared light.
Non-ionizing radiation doesn’t have as much energy as ionizing radiation does. Traditional radiation therapy uses high-energy ionizing radiation to kill cancer cells. Ionizing radiation can damage healthy cells nearby, which can cause side effects.
What are the side effects of TTFields?
Side effects of TTFields devices are usually limited to the electrode sites. They can include:
- Skin irritation
- Allergic reactions
- Local warmth and tingling sensations
- Muscle twitching
- Infections
- Breakdown of the skin (ulcers)
Other side effects are also possible. For example, TTFields devices worn on the scalp can cause:
- Headaches
- Sleep problems
- Mood changes
- Increased risk of seizures
Some people might not be good candidates for treatment with TTFields, because of other health issues they have. Talk to your doctor to learn more about whether this type of treatment might be right for you.
For more information on TTFields
Learn more about how TTFields are used to treat glioblastoma, mesothelioma, and non-small cell lung cancer.
- Written by
- References
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
Batchelor T, Shih HA. Management of glioblastoma in older adults. UpToDate. 2024. Updated August 2023. Accessed at https://www.uptodate.com/contents/management-of-glioblastoma-in-older-adults on July 23, 2024.
Batchelor T, Shih HA, Carter BS. Management of recurrent high-grade gliomas. UpToDate. 2024. Updated July 2024. Accessed at https://www.uptodate.com/contents/management-of-recurrent-high-grade-gliomas on July 22, 2024.
Moser JC, Salvador E, Deniz K, et al. The mechanisms of action of tumor treating fields. Cancer Res. 2022; 82(20):3650–3658. doi.org/10.1158/0008-5472.CAN-22-0887
NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines). Central Nervous System Cancers. Version 1.2024. Updated May 2024. National Comprehensive Cancer Network. Accessed at https://www.nccn.org/professionals/physician_gls/pdf/cns.pdf on July 23, 2024.
Neal JW. Subsequent-line therapy in non-small cell lung cancer lacking an actionable driver mutation. UpToDate. 2024. Accessed at https://www.uptodate.com/contents/subsequent-line-therapy-in-non-small-cell-lung-cancer-lacking-an-actionable-driver-mutation on October 29, 2024.
Tsao AS. Systemic treatment for unresectable malignant pleural mesothelioma. UpToDate. 2024. Updated April 2024. Accessed at https://www.uptodate.com/contents/systemic-treatment-for-unresectable-malignant-pleural-mesothelioma on October 28, 2024.
Last Revised: October 29, 2024
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