What is "photodynamic therapy" or "PDT"?

What is "photodynamic therapy" or "PDT"?

Harry Saperstein, MD, FAAD (Dermatologist, Clinical Assoc. Professor, Medicine, Private Practice and UCLA) gives expert video advice on: How are early-stage melanoma skin cancers treated?; What types of radiation therapy are used to treat skin cancer?; Does laser therapy have a role in treating skin cancer? and more...

Photodynamic therapy or "PDT" is a relatively new modality we have in treating the skin. "Photodynamic therapy" occurs when you put a chemical on the skin and let it sit for several hours. That chemical seeps into the skin and the skin cells and is absorbed by the skin cells. If there are multiple pre-cancers on the skin, they actually preferentially take in the chemical. That chemical is stimulated by light, and so after several hours the patient is put into a light box; that light is not effective on normal skin but on all the skin where the chemical has been absorbed, it causes tremendous reaction and cell death and in so doing can selectively kill multiple actinic keratosis at one time. In so doing, the incident and risk of skin cancers is markedly diminished in the future for that patient.