However, mistletoe plants and berries can be poisonous to humans if eaten. Mistletoe products are not sold commercially in the United States. The CIS is a program of the National Cancer Institute. Laser therapy involves the use of high-intensity light to destroy cancer cells. Ordinary light, such as that in a light bulb, has many wavelengths and spreads in all directions.
Laser light has a single wavelength that is focused in a narrow beam.
Laser light contains a lot of energy. It is powerful enough to cut through steel or shape diamonds and precise enough to cut through human tissue in delicate surgery. Lasers are used in two ways to treat cancer. They can shrink or destroy a tumor with heat. They also can be used with light-sensitive dyes, which are injected into the body, to trigger a chemical reaction that kills cancer cells.