The technology of photodynamic therapy or PDT started in 1990. The procedure is conducted to locate and destroy cancer cells using a light-activated drug. Since it has been introduced, the use of Photofrin was approved by the FDA. Photofrin, also called porfimer sodium, is a light-activated drug used to treat the symptoms of non small cell cancer of the lung as well as cancer of the esophagus where radiotherapy and surgery are not a wise option.

 

Injection and distribution of the drug throughout the patient's body is done by natural methods. The drug leaves the healthy cells faster than the cancer cells. When the photosensitized medication has left the area where healthy tissues are, a light is then beamed into the cancerous tissue in order to activate the drug to produce a type of oxygen that can kill cancer cells. The light comes from a fiber optic device connected to an endoscope and inserted to the body through a minor incision. This light source may also be delivered within the lungs and esophagus for cancer treatment in those areas.

The decision of the physician as to the choice of wavelength and photosensitizer largely depends on the amount of tissue the light must pass through to reach the affected area. Wavelengths define how far within the patient's body the light can travel. Different photosensitizing medications react to different light wavelengths.

PDT, however, may cause damage to the tumors in two ways. One, it denies nutrients because it destroys blood vessels. Two, it stimulates the immune system which causes the patient's body to attack the tumor.

The Limitations of PDT (Photodynamic Therapy)

The use of PDT is limited by the maximum thickness of the tissue its light can penetrate, which is one-third of an inch. Thus it cannot be of much use to cancer growth on or beneath the surface of the skin as well as on the exterior parts of internal organs. Cancerous tumor can be fourteen times denser than normal tissues. As an element of treating malignant mesothelioma, PDT was clinically tested on a minor scale. One study showed that it is not particularly an effective treatment for patients with late-stage mesothelioma if used in combination with immunotherapy, when following surgical resection of the lung or a portion of it.

PDT has been effectively used for treatment of the symptoms of the early stage of mesothelioma. However, the efficacy of PDT on diffused cancer cells was questioned. Diffused cancerous cells usually occur in the late stage of mesothelioma. There is a number of clinical trials conducted to test new photosensitizing drugs for treatment of cancers that are easily located which have been approved by FDA. But as of yet, there is no concentrated effort for developing a treatment with the use of PDT for mesothelioma.

Photodymanic therapy holds some promise; however it is not apparent how it can be useful in multi-modal treatment plans for malignant mesothelioma. Different forms of treatment are coming out that oncologists can use and efforts are being made to see how PDT can be developed as part of the treatment package for mesothelioma.