Laser Therapy
The word LASER stands for Light Amplification by Stimulated Emission of Radiation.
Laser light is different from regular light. The light from the sun or from a light bulb has many different wavelengths and spreads out in all directions. Laser light has a single, high-energy wavelength and can be focused in a very narrow beam. This makes it both powerful and precise.
Lasers can be used instead of blades (scalpels) for careful surgical work, such as repairing a damaged retina in the eye, cutting body tissue, or stopping bleeding. They can also be used to heat and destroy small areas (like some tumors) or activate light-sensitive drugs.
Types of lasers
Lasers are named for the liquid, gas, solid, or electronic substance used to create the light. Many types of lasers are used to treat medical problems, and new ones are being tested. The main types of lasers currently used in cancer treatment include:
- Carbon dioxide (CO2)
- Argon
- Neodymium: yttrium aluminum garnet (Nd: YAG)
Doctors and other health experts who use these lasers need special training in how to use and safely handle them.
Carbon dioxide (CO2) lasers
CO2 lasers don’t go deep into tissues like Nd: YAG lasers. They can cut or vaporize (dissolve) tissue and cause little bleeding. They do little damage to the surrounding or deep tissue. They are used to treat pre-cancers and some early-stage cancers.
Argon lasers
Argon lasers, like CO2 lasers, only go a short distance into tissue. They are useful in treating skin problems and some types of eye tumors. Sometimes, they are used during colonoscopies (tests to look for colon cancer) to remove polyps before they become cancer. They also can be used with light-sensitive drugs to kill cancer cells in a treatment known as photodynamic therapy (PDT).
Another way they can be used is to help stop bleeding by sealing blood vessels in patients who are getting radiation therapy for certain types of cancer. This might be needed because sometimes radiation therapy can damage the blood vessels near tumors, causing them to tear and bleed.
Nd: YAG (Neodymium: Yttrium-Aluminum-Garnet) lasers
Light from this laser can go deeper into tissue than other types of lasers, and it can make blood clot quickly. Nd: YAG lasers can be used through thin flexible tubes called endoscopes to get to hard-to-reach parts inside the body, such as the esophagus (swallowing tube) or the large intestine (colon). This light can also travel through flexible optical fibers (thin, clear tubes) put into a tumor, where the light's heat can destroy it.
Treating cancer with lasers
Lasers can be used in 2 main ways to treat cancer:
- To shrink or destroy a tumor with heat
- To activate a chemical (a photosensitizing agent) that kills only the cancer cells
Lasers can be used alone or with other cancer treatments, such as chemotherapy (chemo) or radiation therapy.
Shrinking or destroying tumors directly
The CO2 and Nd: YAG lasers are used to shrink or destroy tumors. They can be used with thin, flexible tubes called endoscopes. Endoscopes let doctors see and work inside certain parts of the body that could not otherwise be reached except by major surgery. Using an endoscope also helps position the laser beam to hit its target accurately.
Here are some examples of how lasers treat cancer or pre-cancerous conditions:
- Colorectal polyps: Lasers can be used to remove small growths in the colon and rectum that might become cancer called polyps.
- Pre-cancers and early cancers: Lasers can be used to treat some pre-cancers of the skin and cervix, and early cancers of the skin.
- Advanced cancer: Lasers might be used to treat cancers causing a blockage in the airway by destroying a part of the tumor.
- Brain tumors: Laser-induced interstitial thermotherapy (LITT) can be used to treat some brain tumors. It uses heat to help shrink tumors by damaging cells or taking away the things they need to live (like oxygen and food).
Lasers using photodynamic therapy
For most types of photodynamic therapy (PDT), a special drug called a photosensitizing agent is put into the bloodstream. Over time, it is absorbed by body tissues. The drug stays longer in cancer cells than in normal cells.
Photosensitizing agents are turned on or activated by certain types of light. When cancer cells that contain the photosensitizing agent are exposed to light from an argon laser, it causes a chemical reaction that kills them. Light exposure must be carefully timed so that it’s used when most of the agent has left healthy cells but is still in the cancer cells.
PDT is sometimes used to treat cancers and pre-cancers of the esophagus, bile duct, bladder, and certain kinds of lung cancer that can be reached with endoscopes.
It is also being studied for use in other cancers, such as brain, pancreas, and prostate. Researchers are looking at different kinds of lasers and new photosensitizer drugs that might work better.
Treating cancer-related side effects with lasers
Lasers are being studied to treat or prevent side effects of common cancer treatments. For instance, low-level laser therapy (LLLT) might help treat the arm swelling (lymphedema) that can develop after breast surgery when lymph nodes in the armpit are removed. Some studies are looking at LLLT to prevent or treat severe mouth sores caused by chemo. Also, argon lasers can be used to treat rectal bleeding after high-dose prostate radiation.
Benefits and limits of laser treatment
Lasers have some benefits and drawbacks compared with normal surgical tools. Each person’s case is different, so it is important to discuss laser therapy with your doctor to see if it might be right for you.
Benefits of laser treatment
- Lasers are more precise and exact than blades (scalpels) and cause less damage to other tissue.
- The heat produced by lasers helps clean (sterilize) the edges of the body tissue that it’s cutting and reduces the risk of infection.
- Since laser heat seals blood vessels, there is less bleeding, swelling, pain, or scarring.
- Operating time may be shorter.
- Laser surgery may mean less cutting and damage to healthy tissues (it can be less invasive). For example, with fiber optics, laser light can be directed to parts of the body through very small cuts (incisions) without a large incision.
- More procedures may be done in outpatient settings.
- Healing time is shorter.
Limits of laser treatment
- Not many doctors, nurses, and other health experts are trained to use lasers.
- Laser equipment costs a lot of money and is large compared to the usual surgical tools used. Advances in technology are helping to reduce their cost and size.
- Strict safety precautions must be followed when lasers are used. For example, the care team and patient must wear eye protection.
- The effects of some laser treatments might not last long and might need to be repeated.
- Sometimes, the laser cannot remove all of the tumor in one treatment and treatments may need to be repeated. Lasers can’t fully treat large tumors.
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- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
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Khalkhal E, Razzaghi M, Rostami-Nejad M, et al. Evaluation of laser effects on the human body after laser therapy. J Lasers Med Sci. 2020;11(1):91-97. doi:10.15171/jlms.2020.15
National Cancer Institute. Lasers to treat cancer. Updated June 16, 2021. Accessed at https://www.cancer.gov/about-cancer/treatment/types/surgery/lasers on March 14, 2025.
National Cancer Institute. Lymphedema. Updated March 6, 2024. Accessed at https://www.cancer.gov/about-cancer/treatment/side-effects/lymphedema#how-is-lymphedema-treated on March 25, 2025.
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Last Revised: April 4, 2025
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