Photodynamic therapy uses a drug and a special type of light to destroy cancer cells. Find out when it's used.
What it is
Photodynamic therapy (PDT) uses a drug and a special type of light.
The drug is a chemical that makes the skin cells sensitive to light. This is called a photosensitising agent. The light could be a laser or another type of light.
You have the drug as a cream put on to your skin. Or as an injection into your bloodstream. You absorb the drug which makes your cells sensitive to light. Your doctor then shines a special light on the treatment area which destroys the cancer cells.
When you have it
You might have PDT to treat thin non melanoma skin cancers including:
- basal cell cancers
- Bowen's disease
- actinic keratosis (solar keratosis)
Your doctor might suggest PDT if you would otherwise need a lot of surgery. 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. In trials, 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 because the light cannot penetrate far enough into the skin.
You have PDT treatment in the outpatient department at the hospital. Before treatment the doctor removes any crust or scale from the top of the skin cancer.
You apply a cream to the skin cancer and the surrounding skin. The cream contains the light sensitising chemical. You do this between 3 to 6 hours before the PDT treatment.
You might have the light sensitising drug as an injection instead.
Your skin absorbs the drug making the cancer very sensitive to light.
During the treatment
Your doctor focuses a special type of light on the area. The light kills any cells that have absorbed the drug.
You might feel a stinging or burning sensation in the treatment area when the light is on. A fan, painkillers or local anaesthetic can help ease the discomfort.
You can have more than one skin cancer treated at a time. You can have PDT treatment more than once.
Because of the light sensitising drug the treated skin will be more sensitive to sunlight.
A scab forms where you had the treatment and a dressing is used to cover it. The dressing stays on for about 36 hours. Be careful not to bump or knock it.
The scab will heal in about 3 weeks.
You should have 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.
In 2011, 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.