Photodynamic Therapy (PDT)

Form of oxygen therapy that kills cancer cells

By Triston Brewer, Medical Research EditorLast modified: September 16, 2011

Photodynamic Therapy (PDT)

Photodynamic Therapy (PDT)

What is Photodynamic Therapy?

Photodynamic therapy (PDT) uses a drug called a photosensitizer that produces a form of oxygen that kills cells in those affected by cancer. Each photosensitizer works on a specific wavelength that determines how far the light can travel into the body to treat areas of the body. In most cases, this technology is for cancers detected at an early stage.

PDT To Treat Cancer

The first step of photodynamic therapy involves the photosensitizing agent injected into a patient's bloodstream. The agent is then absorbed by cells throughout the body but remains in cancer cells longer than normal cells. About 72 hours following the injection, the cancerous cells are exposed to light. The photosensitizer in the tumor absorbs the light to produce activated oxygen which destroys the nearby tumors.

Photodynamic therapy destroys tumors in two ways. One way is by damaging blood vessels in the cancerous cells, which prevents the cancer from receiving vital nutrients. PDT also may potentially activate the immune system to attack the tumors. Light sources used for PDT can originate from a laser or other sources. Light can be directed though thin fibers that transmit light called fiber optic cables that deliver light to areas inside the body. LEDs (light-emitting diodes) are another source of light used for surface tumor cells. PDT treatment is used as an outpatient procedure and sometimes in conjunction with other therapies such as surgery, radiation, or chemotherapy.

What types of cancer are currently treated with PDT?

PDT has been approved by the FDA to treat esophageal cancer and non-small cell lung cancer. The photosensitizing agent porfimer sodium has been approved by the FDA to use when the cancer inside the patient cannot be treated solely with laser therapy. In addition, it also is used to treat pre-cancerous lesions in patients with Barrett esophagus, a condition that can lead to esophageal cancer.

What are the limitations of PDT?

The light that is required to activate most photosensitizers cannot pass through more than one-third of an inch of tissue, therefore PDT is used primarily to treat cancerous cells lying just below the surface of the skin or on the lining of internal organs. It is also far less effective in treating tumors of a larger size as the light is unable to pass deep into these tumors. Also, PDT cannot be used on cancerous cells that have spread.

Does PDT have any complications or side effects?

The side effects associated with photodynamic therapy can vary from person to person. The side effects can greatly vary depending on factors such as the area of the body treated, the type of PDT drug administered, the amount of time between administration of the drug and application of the light, and the amount of skin sensitivity to light after treatment.

Porfimer sodium is known to make skin and eyes sensitive to light for nearly six weeks after treatment. Therefore, patients are advised by physicians to keep out of direct sunlight and intense indoor light for the bare minimum of six weeks. Also, one of the adverse side effects of PDT is that damage to healthy tissue can often result as photosensitizers tend to build up in tumors. PDT can also cause burns, pain, swelling, and scarring in the patient's healthy tissue. Other possible side effects are related to the area treated which include coughing, difficulty swallowing, stomach pain, painful breathing, and shortness of breath. It should be noted, however, that these side effects are often temporary in most patients.

The Cost of PDT Treatments

The costs for photodynamic therapy depend on alot of factors and it is advisable to consult a physician to find out the treatment course that is right for you. To learn about PDT available in your city, check our directory today for a physician near you.

Find a Photodynamic Therapy Specialist near you.


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This article was written by the medical research team at does not intend for any of the information on this site to be regarded as medical advice - it is meant as a starting point for understanding treatment details and options before contacting a registered, licensed doctor. We advise all patients to seek medical advice from a doctor.
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