Photodynamic therapy

Photodynamic therapy (PDT) is a treatment for several different types of cancer. It uses a light sensitising drug and a very bright light to destroy cancer cells. 

You can have PDT in different ways. How you have it depends on where the cancer is in your body.  

What is photodynamic therapy (PDT)?

Photodynamic therapy (PDT) is a cancer treatment. You have a drug that makes cells sensitive to light. Then the doctor shines a particular type of light on the treatment area. The drug and light combination destroys the cancer cells.

The drug is called a photosensitiser or photosensitising agent. There are different types of light sensitive drug and different kinds of light. The type of drug and light you have depends on where the cancer is in your body.

How PDT works

The cancer cells absorb the light sensitive drug. The doctor then applies light to the area where the cancer is. The light causes the drug to react and produce a type of oxygen that kills the nearby cells. 

Doctors think PDT might also work in other ways to shrink or destroy tumours. These include:

• the light sensitive drug damaging blood vessels in the cancer which stops it from receiving nutrients that it needs
• triggering the immune system to attack the cancer cells

Who can have photodynamic therapy?

PDT is a treatment for several different types of cancer including

• non melanoma skin cancer
• lung cancer
• food pipe (oesophageal) cancer
• some head and neck cancers

Researchers are also looking at PDT for some other types of cancer including prostate cancer.

How you have photodynamic therapy

You can have PDT in different ways. How you have it depends on where the cancer is in your body. There are 2 stages:

The light sensitive drug
First you have the light sensitive drug. How you have the drug depends on your cancer type. You can have it as:

• a cream put directly on to the skin cancer 
• a liquid that you swallow
• an injection into your blood stream

The light treatment
Then the doctor or nurse shines a light on to the treatment area. How long you wait between these 2 stages depends on your cancer type. It might be several hours, or several days.

The doctor or nurse might shine the light:

• directly to your skin -  to treat skin cancer
• through a flexible tube (a scope) - to treat cancers inside your body such as lung or oesophageal cancer

Your doctor or specialist nurse will talk to you beforehand. They will tell you how you will have treatment and exactly what it involves.

Having PDT for skin cancers

The doctor or nurse applies a light sensitizing cream to the skin cancer and the surrounding skin.

After 3 to 6 hours they remove the cream. Your doctor then shines the light on the treatment area for up to 25 minutes. 

They put a dressing over the treatment area. You can go home after the treatment. 

Having PDT for cancers inside your body

Before treatment

First you have the light sensitive medicine. You either have it as a liquid that you swallow. Or it is an injection through a small tube in a vein in the back of your hand.

Having treatment

Two to three days later, you go to the endoscopy department at the hospital. 

You might have medicine to make you sleepy (sedation). Or you might have a general anaesthetic which means you are asleep.

For lung cancers, your doctor puts a long flexible tube called a bronchoscope into your airways. The tube has a small camera on the end so they can see the cancer. They position the end of the tube close to the tumour and shine a low power laser light at it.

For oesophageal cancers, your doctor puts a long flexible tube called an endoscope into your food pipe. The tube has a small camera on the end so they can see the cancer. They position the end of the tube close to the tumour and shine a low power laser light at it.

After treatment

You stay in the endoscopy department or x-ray department until the sedation or anaesthetic wears off. A nurse then takes you back to your ward. You can usually go home that evening.

A few days after the treatment your doctor might need to remove the dead cells. They do this using an endoscopy tube.

Side effects of PDT

Some light sensitising drugs make the skin and eyes sensitive to light for approximately 6 weeks after treatment. This means you need to avoid direct sunlight and bright indoor light for at least 6 weeks. The skin gets very sensitive and may become very red and sore if it is exposed to light during this time.

PDT can cause some damage to nearby healthy tissue. You might notice:

• burns
• swelling
• pain
• scarring

Other side effects of PDT are related to the area where you have had treatment. They can include coughing, trouble swallowing, stomach pains, painful breathing, or breathlessness.

The side effects are usually temporary.

You can read more about side effects of PDT to different parts of the body. There are links above to information about PDT for skin, lung and oesophageal cancer.