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Cancer Glossary Cancer Diet Guide Support Groups

Photodynamic Therapy for Cancer

Photodynamic therapy kills cancer cells using light and photosensitizing agents. These photosensitizing agents are special drugs absorbed by the cancer cells. The drug is non-toxic. However, when the cancer cells are exposed to a certain light, the drug activates, killing the cancer. Photodynamic therapy (PDT) is also known as phototherapy, photoradiation therapy, and photochemotherapy.

Preparation for the Procedure: It is important for the patient to acclimate his/her body to the light sensitivity it will be experiencing during and after the Photodynamic therapy treatment. The patient may cover all windows and skylights in their home as well as turn off all lights in the house before the appointment.

Dress appropriately for the treatment appointment. The patient should wear light colored tightly woven clothes. His/her clothes should cover most of the body and include long sleeves, pants and socks. Gloves, dark sunglasses and a hat with a wide-brim are also recommended to bring along. 

Procedure: PDT is usually an outpatient procedure and doesn’t take long. The photosensitizing agent can be applied to the skin or injected into the blood stream, depending on where the cancer is located. The drug is absorbed into the entire body, even healthy cells. It takes a certain amount of time for the drugs to absorb into the cancer cells. This time period is called drug-to-light interval and varies anywhere from hours to days, depending on what kind of drug is used. The body eliminates much of the drug in the healthy cells over this time.

Since the drug must be exposed to the light in order to be effective, a laser is directed through a thin, glass, fiber optic strand to the cancerous areas. The drug reacts with oxygen and forms a chemical which destroys cancer cells. How the fiber optic strand is applied depends on the type of cancer. For example, when treating esophageal cancer, the fiber optic strand is inserted into the throat through an endoscope. For lung cancer, the strand is inserted into a bronchoscope so it can go into the lungs.

The light is not very strong so there is little or no pain with Photodynamic therapy. The light is used on the affected area from anywhere between 5 to 40 minutes, as necessary based on the size of the tumor. Dead tissue may be removed within a few days.

Types of or Techniques Used: Photodynamic therapy is used in a variety of ways. In addition to killing cancer directly, it is also used to destroy blood vessels feeding the cancer. It can even be used to goad the body’s own immune system into attacking the cancer.

Recovery Time: Recovery time for Photo-dynamic treatment is highly dependent on the type of cancer being treated. The procedure is typically painless and can even be repeated in the same site for multiple treatments and causes little or no scarring after healing takes place. However, the patient may experience light sensitivity for up to 30 days after treatment.

Risks and Side Effects: There are no long term side effects of Photodynamic therapy when used properly; however, it can cause swelling and light sensitivities. The swelling may cause pain or trouble swallowing or breathing.

It may take weeks for the photosensitizing drugs to be completely eliminated from the body so during this time, the patient’s body may be very sensitive to light, especially the skin and eyes. Minor sun exposure can cause burning and blistering within minutes and eyes may be more sensitive to sunlight and different forms of light.

Though patients should definitely avoid the sun, some indoor light exposure is necessary to help break down the drug in the patient’s skin. After about 30 days, a doctor can test skin for signs of lingering photosensitivity from PDT.

There may be other side effects depending on where the Photodynamic therapy treatment was administered. For example, with esophageal cancer the patient may experience nausea, vomiting, high temperature, headache, hiccups or dehydration. Lung cancer treatments may cause blood in the phlegm, pneumonia, bronchitis or trouble breathing.

Always ask your doctor what may be expected with your personal Photodynamic therapy treatment.