How does Photodynamic therapy (PDT) work?

This article has been archived.
For information about this topic, please click here

Lara Bonner Millar, MD
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: August 16, 2011

Share article


PDT is a multistep treatment process. First, the photosensitizer is administered to the patient. The drug takes a certain amount of time to be absorbed by the body; exactly how much time is needed is dependent on the type of photosensitizer that is used, but typically takes a few days. The drug gets absorbed by cells all over the body, however, it stays in cancer cells longer than normal cells. Second, the physician directs a laser light source at the cancer cells. In the case of esophageal and bronchial lesions, this is done using an endoscope or bronchoscope. The amount of time that the laser is used will vary from patient to patient, according to the amount of disease present. In the presence of light from the laser, the photosensitizer will act on and damage the cancer cells. Since the photosensitizing drug is retained longer in the cancer cells, the cancer cells sustain more damage than the healthy cells that have already cleared the drug.

In PDT, cell death occurs through multiple mechanisms. There can be direct damage to cells via interaction between oxygen and the cancer cells. There are also indirect effects, including damage to blood vessels that supply the tumor, both during the treatment and after the treatment is over. Damage to the tumor blood supply during or after PDT will deprive tumor cells of oxygen/nutrients, thereby enhancing responses. Finally, PDT also stimulates the host immune system to attack the cancer cells.


News
NPe6 May Beat Photofrin Photodynamic Therapy in Lung CA

Sep 2, 2011 - NPe6-photodynamic therapy (PDT) is a better treatment for patients with lung cancer than photofrin-PDT, and the efficacy of PDT may improve based on individual expression status of the anti-apoptotic protein Bcl-2 and breast cancer-resistant protein, according to a study published online Aug. 23 in Lasers in Surgery and Medicine.



I Wish You Knew

How cancer patients have changed my life

View More



Blogs and Web Chats

OncoLink Blogs give our readers a chance to react to and comment on key cancer news topics and provides a forum for OncoLink Experts and readers to share opinions and learn from each other.




OncoLink OncoPilot

Facing a new cancer diagnosis or changing the course of your current treatment? Let our cancer nurses help you through!

Learn More