Photodynamic therapy (PDT) is a type of minimally invasive cancer treatment for certain types of cancer. It uses medicines called photosynthesizing agents and light to destroy cancer cells.

PDT is most often used to treat certain cancers in the esophagus, the lungs, and skin. It may also be used to treat tumors that are on or just beneath the skin or on the lining of internal organs. It can also be used to treat certain conditions that can lead to cancer. This sheet tells you more about PDT and what to expect.

With PDT, you're given a medicine called a photosynthesizing agent (photosensitizer) to treat your cancer. This medicine is absorbed by the body's cells. It stays longer in cancer cells than in normal cells. When exposed to a laser or other light source of a certain wavelength, the medicine starts to work. This causes a chemical reaction that produces a form of oxygen that destroys the cancer cells.

The light source is directed at cancer cells, so there is not much damage to normal cells. PDT may also shrink or destroy cancer by damaging blood vessels in the cancer. Or it may cause the immune system to attack the cancer cells.

The most common side effect of PDT is that the skin and eyes become sensitive to light. This occurs because the medicine called porfimer sodium can stay in the body's cells for some time after the treatment. When you are exposed to sunlight or other forms of bright light, the skin can quickly get swollen, sunburned, and blistered. To help prevent a reaction after the treatment, you need to stay away from bright lights and direct sunlight for at least 6 weeks. How long this is needed depends on the type of photosynthesizing agent used.

Other side effects of PDT depend on the part of the body being treated. For example, if the esophagus or lungs were treated, you may have shortness of breath, a cough, stomach pain, or pain when swallowing and breathing. If your skin was treated, you may have redness, stinging, swelling, itching, or blistering. These side effects go away soon after treatment. Your doctor can tell you more about what side effects to expect and how to manage them.

PDT is done in one or more visits. Before the treatment, your doctor will go over the exact type of medicine that will be used and how it will be given. They will also go over your treatment schedule with you. The treatment is done in stages:

• First stage. The medicine is put into a vein and sent into the bloodstream. Or the medicine is put on the skin over the cancer site. The medicine is then given time for the cancer cells to absorb it. This may take from a few hours to a few days.
• Second stage. A laser or LED light source is directed at the cancer site. To treat cancer cells inside the body, a scope and fiberoptic cables may be used. These are tools that can be safely passed into the body to send light to the cancer site. To treat cancer cells on or just under the skin, the light source is shined directly on the site. This is often done using a lamp or machine.

Call 911 if you have any of these:

• Severe shortness of breath, chest pain, or trouble breathing
• Severe trouble swallowing or pain when swallowing
• Coughing up blood

Ask how to contact your doctor, including after hours, weekends, and holidays. Contact your doctor right away if you have any of the following:

• Fever of 100.4ºF (38 ºC) or higher, or as advised by your doctor
• Uncontrolled nausea and vomiting
• Severe redness, swelling, blistering, or skin breakdown
• Severe pain due to skin irritation
• Any new symptom, or one that causes concern

You'll have one or more follow-up visits with your doctor. At these visits, your doctor will monitor your health and response to the treatment. If you need more tests or treatments, your doctor will talk about these with you.