This also from the Mayo Clinic and their use of PDT and Protofrin. Seems that the Mayo thinks well of this form of treatment for Barrett's Esophagus....AXCA is looking more and more interesting to me...
Photodynamic Therapy
What is photodynamic therapy?
Photodynamic therapy (PDT) is a two-part treatment using a photosensitizing drug and red, non-thermal laser light. The photosensitizer drug is a light-activated chemical such as Photofrin (profimer sodium), which selectively accumulates in cancerous and precancerous tissue.
This drug is administered intravenously. Two days later, the photosensitizer is activated by exposing the tissue to light energy of a specific wavelength. When the light hits the photosensitizer in the presence of oxygen, a highly reactive single oxygen radical that destroys the cancerous tissue is generate. This type of laser light is different from radiation therapy or heat-producing lasers.
PDT can be repeated several times without harming normal body tissues and can be used alone or in conjuction with other treatments, such as chemotherapy or radiation therapy. In the digestive tract, this laser light is delivered during an upper endoscopy. Patients are under conscious sedation for the procedure, meaning they are sleepy and pain free but breathing on their own. PDT is now a routine, outpatient treatment.
Photodynamic therapy is used to treat the following:
Barrett's esophagus
Early esophageal cancer (adenocarcinoma or squamous cell carcinoma)
Obstructing esophageal cancer (often used in place of, or in conjuction with, chemotherapy or radiation therapy)
Persistent or recurrent esophageal cancer after surgery, chemotherapy or radiation therapy
Gastric cancer
Lung cancer
How does PDT work?
First, patients are given an injection of the photoactive drug Photofrin, which is absorbed into the body's tissues, especially the cancerous cells. Over the next several days, the drug is mostly eliminated from normal tissue but is retained in cancerous tissue and precancerous cells. It also remains in the skin for about four weeks.
Two days after the Photofrin is infused, the patient will undergo upper endoscopy under conscious sedation. This is an outpatient, office procedure where the patient is sedated using medications such as Demerol and Versed, which are similar to morphine and Valium. During this procedure, non-thermal light from a laser, carried by a fiberoptic guide, is passed through the endoscope and directed at the cancer tissue in the esophagus. This painless procedure usually lasts about 30 minutes. Complications are rare.
The laser light activates the Photofrin contained in the cancerous cells and produces a chain reaction that destroys the cells. Since Photofrin is mostly contained in the cancerous cells, there is relatively less damage to the surrounding normal tissue. Neither the drug nor the laser light by themselves have any effect. It is this unique reaction between laser light and Photofrin that makes photodynamic therapy possible.
What are the possible side effects?
There are two major side effects associated with photodynamic therapy:
Local swelling and inflammation occurs in and around the esophagus, which may cause chest discomfort, along with nausea, fever and constipation. These symptoms are usually controlled with the limited use of pain relievers and other medications.
Photosensitivity (sensitivity of body tissues to light) always occurs after PDT and lasts for about four weeks. From the moment a patient is injected with Photofrin, the skin and eyes will be very sensitive to bright light. Exposure to bright light or direct sunlight must be carefully avoided to prevent sunburn, redness and swelling. Photosensitivity reactions can occur in a matter of minutes, so it is important to take precautions to shield the skin and eyes from intense light exposure.
What are the precautions can be taken to prevent a photosensitivity reaction?
Patients must be careful during the first 30 days after the Photofrin injection to avoid bright lights and direct sunlight, even on cloudy days. They should not, however, stay in a dark room all the time! It is important for patients to be exposed to indoor lights, and this will help make them less photosensitive.
The lighting usually found in homes is not harmful. However, patients must stay away from direct sunlight, including sunlight that shines through a window or skylight. Most indoor activities such as watching TV are completely safe. When reading, the patient must take care not to come too close to a high-intensity reading lamp.
For routine activities such as shopping or going to the movies, it is best to wait until sundown. During daylight hours, the patient must cover as much skin as possible. This means wearing a long-sleeved shirt, slacks, gloves, socks, shoes and a wide-brimmed hat. The clothes should be tightly woven, light-colored fabrics, if possible. Patients should protect their eyes by wearing dark sunglasses. These precautions are required even on cloudy days and especially when traveling in a vehicle.
The use of sunscreens, no matter how high the SPF, will not protect against these photosensitivity reactions. These reactions, when they occur, look like a severe sunburn. The skin will be red, swollen and may blister. Severe reactions may require medical treatment.
What is the cost of PDT treatment?
Since 1995, PDT used for the treatment of esophageal cancer has been approved by the U.S. Food and Drug Administration. We have had little difficulty receiving coverage from Medicare or insurance companies. Insurance coverage for treatment of Barrett's esophagus is always on a case-by-case basis. |
