Photodynamic therapy (PDT) uses medications to make cancer cells and other abnormal cells vulnerable to high-intensity light energy, such as from lasers. It can be used to treat a variety of cancerous and precancerous conditions.

Photodynamic therapy involves applying or infusing a special drug (photosensitizer) that makes the cells light sensitive. For cancers on or near the surface of the skin, the drug may be applied topically. For other cancers, the drug may be infused into a vein.

After the photosensitizer is taken up by the target tissue, your doctor exposes the cancer cells to a specific wavelength and energy of light that activates the drug and destroys the cancerous or precancerous cells. For cancers inside the body, this may require passing the light down a thin, flexible tube and into your esophagus or your windpipe (trachea) to reach the area.

The light kills the cells that have absorbed the light-sensitive medication.