Photodynamic therapy (PDT)

Photodynamic therapy (PDT) is used to treat cancers of the:

  • skin (not melanoma)
  • head and neck
  • mouth
  • lung
  • gullet.

It is also used to treat some pre-cancerous conditions.

PDT is usually given in two stages.

First, you are given a light-sensitive drug. For skin cancers, it may be a cream. For internal cancers it may be an injection into a vein, or sometimes a drink. After you have had the drug, you will need to wait for it to build up in the cancer cells before having the second stage. This could be a few hours or a few days.

Stage 2 involves a special light (usually a laser) being shone on to the cancer. The light activates the drug to treat the tumour. If the cancer is internal, an ultrasound or scan may be used to deliver the light to the tumour.

The possible side effects depend on which part of the body is treated, the drugs used, and your reaction. You may become sensitive to light for a time, and will need to take care in the sun, or other bright lights.

How PDT works

Photodynamic therapy (PDT) is a treatment that uses a light-sensitive drug and a laser or light source to destroy cancer cells.

The drug is attracted to the cancer cells. But it does not become active in these cells until a light is shone on it. Using a certain light or laser will activate the drug to release a type of oxygen that kills the nearby cancer cells.

Some healthy, normal cells in the body will also be affected by PDT, but these cells usually recover after treatment.

PDT is not widely available around the UK, so you may have to travel to have it.

When PDT is used

Treating cancer

PDT can be used to treat some types of cancer. These include:

PDT can also be used when the cancer or affected area is on, or near, the lining of internal organs.

When PDT is used to treat early-stage cancers, the aim is to try to cure the cancer. PDT can sometimes be used to treat small, early lung cancers in people who can't have surgery.

It may also be given alongside surgery, as part of a clinical trial, to treat a type of brain tumour called glioblastoma multiforme.

When PDT is used for more advanced cancers, the aim is to shrink the cancer and reduce symptoms. It can sometimes be used to relieve breathlessness and improve swallowing in people with advanced cancer of the lung or the gullet (oesophagus).

Researchers are trying to find out which types of cancer PDT works best for. Clinical trials are looking at new light-sensitive drugs and new laser and non-laser light treatments. They are also trying to find ways of reducing the side effects. You may be offered PDT as part of a trial.

Your hospital doctor can tell you whether PDT is the right treatment in your situation.

Treating pre-cancerous conditions

PDT is also used to treat some pre-cancerous conditions, including:

  • Barrett's oesophagus – where the cells of the oesophagus (gullet) grow abnormally.
  • Bowen's disease – where the cells in the outer layer of the skin grow abnormally.
  • actinic keratoses – scaly dry patches of skin caused by sun damage.

Some research studies have used PDT to treat pre-cancerous changes in the cells of the vagina, anus and vulva.

How PDT is given

The treatment is normally given in two stages.

Stage 1

The first stage of treatment is when you are given the light sensitive drug. If you have skin cancer, the drug is usually applied to your skin as a cream. For cancers that are inside the body, the drug may be given as an injection into a vein (intravenously). Occasionally it is given as a drink.

Once you have had the drug, there is a delay before the second stage of treatment. This allows time for the drug to build up in the cancer cells. The time you wait after having the drug may be a few hours or a few days. This will depend on the type of cancer you have and its treatment. You will usually be able to go home during this time.

There are different types of light sensitive drug. The most common are:

  • 5-aminolevulinic acid (5-ALA)
  • temoporfin (Foscan®)
  • porfimer sodium (Photofrin®)

The drug used will depend on the type of cancer you have and which is best for your situation. Your doctor or nurse will explain more about this and tell you how the drug is given.

Stage 2

The second stage of treatment involves shining a laser, or sometimes a non-laser, light on to the cancer or the affected area.

For treatment to the skin, the light is shone straight on to the skin. For cancers inside the body, a flexible tube (endoscope) may need to be passed into your body to guide the light to the affected area. A scan or ultrasound may be used to help direct the light to the right part of the body.

Possible side effects of PDT

The side effects of PDT will be different for each person and depend on:

  • the area of the body being treated
  • the type of light sensitive drug
  • the amount of time between the stages of treatment
  • how sensitive your skin is to light after the treatment.

We explain the possible side effects of PDT for different cancers or areas of the body below.

PDT for skin cancer and Bowen's disease

PDT can be used instead of surgery to treat basal cell skin cancers and Bowen's disease (a pre-cancerous skin condition). It is also used to treat areas of raised, rough skin that are sensitive to the sun (known as actinic keratoses). These have a small risk of developing into skin cancer.

Before your treatment, your nurse or doctor will remove any crusting from the affected area of skin. This makes it easier for the light sensitive drug in the cream to reach the affected cells. They will then apply the cream to the affected area and cover it with a dressing to protect it.

You will have to wait about 3 to 6 hours to allow time for the cream to work before you have the second stage of your treatment. The length of time you wait varies, depending on the skin condition being treated.

In the second stage of treatment, you will be asked to sit or lie down in a comfortable position. A strong light is shone directly on to the affected skin. This can take up to 45 minutes, depending on your specific treatment. The treatment is usually repeated a week later, you will go home during this time.

Possible side effects

Sensitivity to light

The treated area of skin will be sensitive to daylight and bright, indoor lighting. This will probably last for 24 to 36 hours. You will need to keep the treated area of skin covered during this time. After that, you can wash and have a bath or shower as usual. It is important to treat your skin gently and avoid rubbing the area until it has healed.


When you are having the treatment you may feel a bit of discomfort, like a burning sensation. A cooling fan or a water spray, or both, may help with this. Some hospitals use a special machine that delivers cool air to the treated area.

Taking painkillers before the treatment may also help. You may have a local anaesthetic to numb the area before the treatment. You may be given some steroid cream to apply at home if your skin is still sore.


You will get a scab on the treated area. This usually falls off after about three weeks. The area usually heals quickly without scarring.

PDT for head and neck cancers

PDT may be used for early-stage cancers of the head and neck to try to cure the cancer. It is usually given as part of a clinical trial. PDT can also be used in advanced cancer to shrink the tumour and reduce symptoms.

First, you have the light sensitive drug as an injection through a small tube (cannula) inserted into a vein. This takes a few minutes and then the tube is removed.

You will have to wait up to four days before having the second stage of your treatment (when the light is directed at the cancer cells). Your doctor will tell you when you need to come back to the hospital for this.

Usually only one treatment is given, although some people need a second treatment a few weeks later.

Possible side effects

Sensitivity to light

The light sensitive drugs will mostly build up in the cancer cells. But normal cells can also be affected, so your skin and eyes may also become very sensitive to light. You will gradually become less sensitive to light and things will return to normal. The time this takes will depend on which drugs you had.

The drug that is most commonly used to treat head and neck cancers can make you sensitive to sunlight for up to a month. During this period, you will be given specific advice from your hospital team about protecting yourself from sunlight and bright indoor lighting. You will need to follow this advice carefully to avoid burning your skin.

Your hospital team will give you advice on using lights inside your home, as well as other ways to avoid or reduce your exposure to strong lights. Strong lights include spotlights, fire, TV or even sunlight shining through a window. You will also be told when you can go outside and what clothing you should wear to protect your skin from sunlight. You may be given a portable light meter to measure the levels of light. The staff who are treating you will explain how to use it.

Eye checks

You should avoid having your eyes checked and light shone into your eyes while you are sensitive to light. This is because the area at the back of your eye (retina) will be more sensitive to light than usual.


PDT can cause pain in the treated area. This can usually be controlled with painkillers. Let your doctor or specialist nurse know if you have any pain so they can give you some painkillers.


Some light sensitive drugs can cause swelling in the treated area. If you have had treatment in your mouth or throat, this may make it difficult for you to swallow. It is important to let your nurse or doctor know straight away if you have difficulties swallowing.

The swelling is temporary but can be treated with steroid injections or drugs that help reduce it.

Feeling sick (nausea)

Some people may feel sick, but this can be controlled with anti-sickness (anti-emetic) tablets. Let your doctor or nurse know if you feel sick.

PDT for lung cancer

PDT to your lung can make you sensitive to light for up to a month. You will be given specific advice from your treatment team on how to protect yourself from the sun and other strong lights. It is important to follow the advice carefully to avoid burning your skin.

You may cough up more sputum (mucus), and it may be bloodstained. You may also have some pain in the part of the chest that has been treated. Let your doctor know if you have any pain and they can prescribe painkillers.

PDT for cancer and pre-cancer of the gullet (oesophagus)

You may have swelling in the treatment area. This may make you feel sick and cause some chest pain. You may find swallowing difficult for a few days. Talk to your doctor if you have any of these symptoms, they may be able to give you medicines that can help.

PDT for brain tumours

Possible side effects of PDT for brain tumours may include swelling and increased pressure in the brain. Your doctor and nurses will check you very carefully for these types of side effects. Let them know about any side effects you have.

Back to Other treatments

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