What is photodynamic therapy (PDT)?

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

The cancer cells absorb the light-sensitive drug. Then a doctor shines a special light or laser on the cells. This activates the drug to release a type of oxygen that kills the cancer cells.

Some healthy, normal cells in the body are also affected by PDT. These cells usually recover after treatment.

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

When PDT is used

PDT for cancer

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

A similar treatment called photodynamic diagnosis (PDD) can be used for:

PDD helps to diagnose and treat these cancers at the same time. The light-sensitive drug makes the cancer visible, so that a surgeon can remove it.

We have information about PDT to different areas of the body and its side effects on this page. It is important to tell your PDT treatment team about any side effects you have. It is best to read this information with our general information about the type of cancer you have.

When PDT is used to treat early-stage cancers, the aim is to cure the cancer. When PDT is used for more advanced cancers, the aim is to shrink the cancer and reduce symptoms.

Researchers are trying to find out which types of cancer PDT works best for. Clinical trials are looking at new:

  • light-sensitive drugs
  • laser light treatments
  • non-laser light treatments
  • ways of reducing the side effects.

Sometimes PDT cannot be used. This depends on where the cancer is in the body. Your hospital doctor can tell you whether PDT is the right treatment for you.

PDT for pre-cancerous conditions

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

How PDT is given

The treatment is usually given in two stages.

Stage 1

Your doctor or nurse gives you the light-sensitive drug.

If you have skin cancer, they apply the drug to your skin as a cream. If the cancer is inside the body, they may give the drug as an injection into a vein (intravenously). Sometimes the drug is given as a drink.

When you have had the drug, you wait for it to build up in the cancer cells. This may take a few hours to a few days, depending on the type of drug used. For some treatments, you may be able to go home during this time.

There are different types of light-sensitive drug. The drug you are given will depend on the type of cancer you have, and which treatment 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.

PDT to the skin

PDT can be used to treat:

We have more information about PDT for skin cancer. PDT for Bowen’s disease and actinic keratoses is given in the same way.

Daylight PDT (dPDT)

Some PDT centres offer daylight PDT to treat the skin. It is usually used to treat areas on the head or face. The doctor or nurse applies the light-sensitive cream. Then natural daylight activates the treatment. You may have to sit outside or in a conservatory if you have access to one. You usually sit in the daylight for 2 to 3 hours, with the affected area uncovered. Your nurses will talk to you about using suncream, if you need it.

In the UK, daylight PDT is only possible between April and October. If rain is forecast, the hospital will contact you to arrange your treatment for a different day.

Side effects are similar to the side effects for standard PDT to the skin. But daylight PDT usually causes less discomfort.

Possible side effects

Sensitivity to light

The treated area of skin will be sensitive to daylight and bright, indoor lighting. This will last for around 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 while it is sensitive.

Pain

When you are having the treatment, you may feel a burning sensation. Some people find this uncomfortable or painful. A cooling fan or a water spray, or both, may help with this. Some hospitals use a machine that delivers cool air to the treated area.

Your nurse may give you painkillers before the treatment. Or they may apply a local anaesthetic to numb the area.

Your skin may be sore for a few days after treatment. Your doctor may give you some steroid cream to help with this. Or they may tell you to take mild painkillers if you need to. If you still have pain, tell your treatment centre.

Healing

You may get a scab on the treated area. This usually falls off after about 2 weeks. The area usually heals quickly without scarring.

PDT for head and neck cancers

You may have PDT for an advanced head and neck cancer. The aim of treatment is to shrink the tumour and reduce symptoms. It is usually given as part of a clinical trial.

Your doctor or nurse gives you the light-sensitive drug as an injection into a vein. You then wait up to 4 days before stage two of your treatment. This involves having light directed at the cancer cells. Your doctor will tell you when you need to come back to the hospital for this.

Usually you only need one treatment of PDT.

Possible side effects

Sensitivity to light

Your skin and eyes may become very sensitive to light after PDT for head and neck cancer. This slowly returns to normal. The time this takes depends on which drugs you had, but it is usually around 4 weeks.

Your treatment team will tell you how to protect yourself from light. This includes daylight and bright indoor lighting. They will also tell you when you can go outside and what you should wear to protect your eyes and skin from daylight. They may give you a portable light meter to measure the levels of light.

It is important to follow this advice carefully to protect your eyes and avoid burning your skin.

While you are sensitive to light, it is important not to have:

  • your eyes checked
  • light shone into your eyes.

This is because the area at the back of your eye (retina) will be more sensitive to light than usual.

Pain

PDT can cause pain in the treated area. Tell your doctor or specialist nurse if you have any pain so they can give you painkillers.

Swelling

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 tell your nurse or doctor straight away if this happens. The swelling will not last long, but steroid injections or drugs can help to reduce it if needed.

Feeling sick (nausea)

Some people may feel sick. Anti-sickness (anti-emetic) tablets can control this. Tell your doctor or nurse if you feel sick.

PDT for lung cancer

You may have PDT to treat a small, early lung cancer if you cannot have surgery. It may also help with breathlessness if you have advanced cancer of the lung.

Your doctor or nurse gives you the light-sensitive drug as an injection into a vein. They usually give the second stage of treatment 1 to 3 days later. They use a bronchoscope to direct the light at the area being treated. This is a thin, flexible tube that looks inside your airways and lungs.

Possible side effects

Mucus

You may cough up more mucus (sputum). This may contain blood.

Chest pain

Some people may also have some pain in the part of the chest that has been treated. Tell your doctor straight away if you have any chest pain. They may prescribe painkillers.

Sensitivity to light

Your skin and eyes may become very sensitive to light after PDT for lung cancer. This slowly returns to normal. The time this takes depends on which drugs you had, but it is usually around 6 to 8 weeks.

Your treatment team will give you advice about protecting yourself from light. This includes daylight and bright indoor lighting. They will also tell you when you can go outside and what you should wear to protect your eyes and skin from daylight. They may give you a portable light meter to measure the levels of light.

It is important to follow this advice carefully to protect your eyes and avoid burning your skin.

While you are sensitive to light, it is important not to have:

  • your eyes checked
  • light shone into your eyes.

This is because the area at the back of your eye (retina) will be more sensitive to light than usual.

PDT to the eye

PDT is sometimes used to treat ocular melanoma.

Your doctor or nurse gives the light-sensitive drug as an injection into a vein. You will have the light treatment a few minutes after this.

Possible side effects

Sensitivity to light

Your skin and eyes may become very sensitive to light after PDT to the eye. This slowly returns to normal. The time this takes depends on which drugs you had, but it is usually around 48 hours.

Your treatment team will give you advice about protecting yourself from light. This includes daylight and bright indoor lighting. They will also tell you when you can go outside and what you should wear to protect your eyes and skin from daylight. They may give you a portable light meter to measure the levels of light.

It is important to follow this advice carefully to protect your eyes and avoid burning your skin.

While you are sensitive to light it is important not to have:

  • your eyes checked
  • light shone into your eyes.

This is because the area at the back of your eye (retina) will be more sensitive to light than usual.

Photodynamic diagnosis (PDD) for brain tumours

PDD for brain tumours is given at the same time as surgery. Your nurse gives you a light-sensitive drug called 5-ALA (Gliolan) as a drink 2 to 4 hours before the operation. It is sometimes called ‘the pink drink’.

During surgery, 5-ALA makes brain tumour cells glow pink or red under a blue light. This may help the doctor decide which areas to remove.

Possible side effects

Most side effects of PDD for brain tumours are from the surgery. They may include swelling and increased pressure in the brain. Your doctor and nurses will check you very carefully for these types of side effects. Tell them about any side effects you have.

Sensitivity to light

Your skin will be sensitive to light. This slowly returns to normal. The time this takes depends on which drugs you had, but it is usually within 48 hours. You will be in the hospital during this time so you do not need to take any extra precautions.

PDD for bladder cancer

PDD can be used to treat non-invasive bladder cancer. It is also called blue-light cystoscopy.

The nurse puts a tube (catheter) up the urethra and into the bladder. The urethra is the tube that carries urine (pee) out of your body from the bladder. The nurse uses the catheter to empty your bladder. They then put the light-sensitive drug into the bladder through the catheter. The drug stays in your bladder for about 1 hour. The nurse or surgeon then empties your bladder through the catheter.

You then have an operation to remove cancer from inside the bladder. This is called a TURBT (transurethral resection of a bladder tumour). The doctor uses a tube called a cystoscope. This has a light and a camera on the end. The drug makes the cancer cells glow pink under a blue light. This may help the doctor decide which areas to remove.

Possible side effects

Most side effects of PDD for bladder cancer are from the surgery. Your skin does not become sensitive to light with this treatment.

About our information

  • References

     

    Below is a sample of the sources used in our supportive treatment information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    TH Wong et al. British Association of Dermatologists and British Photodermatology Group guidelines for topical photodynamic therapy 2018. British Journal of Dermatology Apr 2019; Vol.180(4):730-739. Available from: https://pubmed.ncbi.nlm.nih.gov/30506819/ (accessed June 2019)

    P Rundle. Photodynamic Therapy for Eye Cancer. 2017.Biomedicines Vol.8;5(4):69. Available from https://pubmed.ncbi.nlm.nih.gov/29292745/. (accessed June 2019)

     


  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.