Photodynamic Cancer Therapy (PCT) employs light sources, such as laser, and a light-sensitive drug in order to destroy cancerous cells. The drug is a photosensitising agent, and it is attracted to cancer cells. However, only when it is hit with a specific type of light does it become active. Hence, the light is directed to the areas where tumour are present, activating the drug and destroying the cells. Unfortunately, healthy cells also get affected by photodynamic therapy, but these do heal reasonably quickly.
When Is Photodynamic Treatment Used?
Photoradiation therapy is only suitable for certain cancers, as well as a number of pre-cancerous conditions. It is only used in those people where the cancer is very close to the lining of various internal organs. As such, it is often a viable cancer treatment for cancer of:
• The head and neck
• The oesophagus (gullet)
• The mouth
• The lungs
• The skin (although it is not a suitable treatment for melanoma)
Current research is trying to determine which types of cancer react best to PDT. Additionally, further research is being done in terms of photosensitising agents, light treatments (laser and non-laser) and a reduction of the side effects of PDT. Because research is ongoing, cancer patients are often offered the treatment as a trial.
There are a number of pre-cancerous conditions that seem to be particularly receptive to PDT. These are Bowe’s disease (of the skin) and Barrett’s Oesophagus. Additionally, there is some research to suggest that the treatment may also be beneficial for cancer of the vulva (VIN or vulval intraepithelial neoplasia), the anus and the vagina.
The aim of photochemotherapy is to actually eliminate and destroy the cancer. This is possible if it is caught early enough. However, if the cancer is too advanced, then PDT is used to reduce the symptoms by shrinking the tumour. A medical professional is best suited to advising whether PDT is an appropriate treatment option.
There are two stages within PDT treatment:
1. Administration of the photosensitising agent. This is done as a cream for skin cancers. Internal cancers require the drug to be administered either by injection or intravenously, although injection to the source is generally preferred. The drug is then given the time to travel to the cancer cells, which can take anything from just a few hours to several days. Various drugs are used in this part of the treatment and it depends mainly on the type of cancer you are suffering from.
2. During the second stage, a laser or other light source will be directed onto the cancer itself. With skin cancer, this is obviously done directly to the skin. However, if the cancer is internal, then an endoscope is generally used in order for the laser to be delivered at the site of the tumour itself. To direct the laser, an ultrasound is generally employed.
PDT Side Effects
The side effects of PDT vary from person to person and also depend on the type of person. Some of the things that are of influence on how severe the side effects are, and what type they are include:
• Which part of the body is receiving treatment.
• Which photosensitising drug has been used.
• How much time has elapsed before the light is applied.
• How sensitive the skin becomes to light after the treatment itself.