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Photodynamic Therapy (PDT)

Photodynamic therapy (PDT) uses a drug and a special type of light to kill cancer cells.

You have the drug as a cream put onto your skin. Or as an injection into your bloodstream. Your skin soaks up the drug which makes your cells sensitive to light. This is a called a photosensitising agent. Your doctor then shines a special light on the treatment area which destroys the cancer cells. The light could be a laser or another type of light. 

When you have it

You might have PDT to treat thin non melanoma skin cancers including:

  • some basal cell cancers (BCC's)
  • Bowen's disease (squamous cell carcinoma in situ)
  • actinic keratosis (solar keratosis)

Your doctor might suggest PDT treatment if surgery could cause poor appearance changes. So you might have it if you have a large skin cancer that is not too deep. Or if you have several cancers in an area. Clinical trials have shown that the appearance of the skin after PDT is better than after surgery.

PDT is not suitable for deep basal cell cancers or squamous cell skin cancers. This is because the light cannot enter the skin deep enough.

For actinic keratosis you usually have one treatment. For basal cell cancer or Bowen’s disease you usually have two treatments 7 days apart. This is one cycle of treatment.

Your doctor will tell you what’s best for your type of cancer. 

Before treatment

You have PDT treatment in the outpatient department at the hospital. 

Before treatment, the doctor cleans the area and removes any crust or scale from the top of the skin cancer. This doesn't cause any pain.

They apply a cream to the skin cancer and the surrounding skin. You have a dressing on top to keep the cream in the right spot and stop you from rubbing it off. 

You do this for up to 3 to 6 hours before the PDT treatment.   

You might have the light sensitising drug as an injection into a vein instead.  

During the treatment

After 3 to 6 hours your doctor cleans the cream away.

You'll get a pair of sunglasses to wear during your treatment to protect your eyes from the light. 

Your doctor then focuses the light on the area that needs treating. The light kills any cells that have absorbed the drug. The light is usually red in colour. 

With the red light, you usually have it shone on your skin for about 10 to 15 minutes. But this will depend on which light your doctor is using.

You might feel a stinging or burning sensation in the treatment area when the light is on. A fan, painkillers or numbing injection (local anaesthetic) can help ease the discomfort. Or your doctor may pause the treatment for a short time. 

You can have more than one skin cancer treated at a time. 

After treatment

Because of the light sensitising drug the treated skin will be more sensitive to sunlight. The British Association of Dermatologists recommends that you wear sunscreen of SPF 30 or more for a least 48 hours. 

A scab forms where you had the treatment and you have a dressing in place to cover it. The dressing stays on for about 36 hours. Be careful not to bump or knock it. You need to also keep the dressing dry. 

The scab usually heals in about 3 weeks. 

You'll get specific instructions about protecting your skin if you have the light sensitising drug into a vein. You might need to avoid bright light or sunlight for a time. This is because all of your skin may be more sensitive to sunlight.  

Ask the doctor or nurse if you are not sure about what to do after treatment. 

You might need another treatment about 4 weeks later if your skin cancer was thick or deep. 

You might have a second cycle of treatment after 3 months if your cancer has partly worked. 

Side effects of PDT

It is common after PDT to have some pain and discomfort from the treatment for a few days. Taking regular painkillers such as paracetamol can help.

The treated area might have some inflammation so it may look pink, red and swollen. The site might also ooze or develop a crust. This should get better after a few days. But if you are worried contact your advice line about this.

Ambulight guidance

The National Institute of Health and Care Excellence (NICE) published guidance on a particular type of PDT called Ambulight. This photodynamic therapy can be given in places outside hospitals, for example in patients’ homes. It is thought that it may cause less pain than normal photodynamic therapy. But NICE said that although doctors can choose to use Ambulight PDT there is not much evidence about how well it works.

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