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Photodynamic Therapy (PDT)

Using a cream and a light source, this minimally invasive treatment is well tolerated, and mainly used for small early BCCs or superficial lesions. One of our Dermatologists at Q Dermatology will prepare the area with light curettage before a topical photosensitising agent is applied to the affected area. After it has had time to be absorbed, the photosensitising agent is then activated by a specific wavelength with a special light. The activated agent selectively destroys only the skin cancer cells, with minimal damage to the surrounding tissue. PDT can produce an excellent cosmetic result with minimal scarring, but is only used for low risk skin cancers. Talk to your dermatologist to decide if this is an appropriate treatment for you. Medicare does not provide a rebate for PDT, so you will be given an out of pocket cost prior to the procedure.

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What is PDT, and what is it used for?

Photodynamic therapy (PDT) is a non-surgical treatment for superficial types of skin cancer.

PDT is effective in treating actinic keratoses (precancerous sun spots) intraepithelial carcinomas (IECs/Bowen’s disease), and superficial basal cell carcinomas (early superficial skin cancers).

How is the treatment performed?

The area to be treated is confirmed with you by your doctor, and then numbed with local anaesthetic. Any scaly areas are curetted (scraped) to remove the scale. ALA or MAL/Metvix cream is then rubbed in to the area, with a thin dressing applied over the cream.

What happens next depends on whether you are receiving blue or red light PDT, or daylight PDT. These treatments vary in terms of timing, and the source of light used to activate the cream.

Blue and red light PDT

For blue light PDT, the ALA cream is allowed one hour to absorb before a bright light is used to activate it

For red light, the MAL cream is allowed three hours to absorb before a bright light is used to activate it.

You can leave the clinic during the time the cream takes to absorb. Please avoid any significant exposure to sunlight, and any strenuous activity that would cause you to sweat under the dressing.

Provided you have no medical reason not to, please take Paracetamol 1000mg 1 hour prior to returning to the clinic.

When you return, the dressing is removed. The skin is then exposed to the bright light for several minutes. This will feel hot and prickly. If the discomfort is significant, the treatment is paused and further local anaesthetic is injected into the area. Most patients find the treatment very tolerable with the local anaesthetic. You will have eye goggles on during the treatment, so you won’t be able to see but a nurse or clinical assistant will sit with you during treatment.

Daylight PDT

This is a very similar process, but uses two hours of natural daylight to activate the cream, rather than the blue or red light. Sunscreen is applied before the MAL cream to all sites, including the treatment area.

After the cream is applied, you then go outside within 30 minutes. A longer delay in exposure leads to greater pain.

After two hours outdoors, the cream should be washed off with plain water or saline. You can return to the clinic to do this, or do this at home. Remain indoors for the rest of the day, and for two days afterwards.

How does PDT work?

Methyl aminolevulinic acid (MAL) (the active agent in the Metvix cream) or ALA is absorbed through the skin to concentrate in the cancer cells.

The reaction that occurs between the MAL/ALA, light, and oxygen causes the cancer cells to die.

How well does PDT work? How many treatments will I need?

Approximately 80% of actinic keratoses clear with one episode of PDT.

Approximately 80% of IECs (intraepithelial carcinomas/Bowen's disease) clear with two episodes of PDT.

Only parts of your face are treated at any one time. For a number of reasons, it is not practical to treat your entire face in one episode. Multiple episodes of treatment may therefore be required.

The nature of sun damage dictates that you may well require repeated episodes of PDT in the future, to areas that have been treated previously.

What are the side effects?

You will feel discomfort when the local anaesthetic is injected.

When exposed to the red/blue light, it is normal for your skin to feel hot, prickly and irritated.

For 12 hours after treatment, it is normal for your skin to feel tender. The pain typically resolves by the next day. Your skin may appear swollen, particularly around your eyes, for 2 - 3 days.

Most people find that their skin is red, puffy, crusty/peeling and sensitive for up to 2 weeks. The worst of this is typically over by day 7. Some people feel comfortable returning to work on the third or fourth day. If you have a public-facing job, you may prefer to take 1 - 2 weeks off. Makeup can generally be applied 5 – 7 days post PDT.

Some patients develop pustules (pimple-like bumps) on their skin after treatment, which usually settle on their own. The skin is often very weepy for the first few days.

Patients with rosy complexions, and those prone to rosacea, may find that the redness and sensitivity takes many weeks to settle after treatment, particularly on the nose.

What should I buy before treatment?

  • An ice pack
  • A large tub of Vaseline
  • A bulk-pack of kitchen Chux cloths

How should I care for my skin after treatment?

You should apply ice packs (wrapped in a Chux cloth or clean teatowel) for 10 minutes every hour for the first day. This helps with discomfort and swelling.

You must avoid the sun COMPLETELY for at least 48 hours following treatment. You need to go directly home from the clinic, wearing a broad-brimmed hat, and not go outside again for at least 2 days. The curtains should be drawn at home during this time, to absolutely minimise your exposure to sunlight.

For the first 3 - 4 days after treatment, perform the following regimen 4 times daily:

  • Make up a bowl of cooled salty water (1 teaspoon of salt in a bowl)
  • Dip a clean Chux in the bowl, and then let the Chux lie on your skin for 10 minutes. It’s often easiest to do this lying down, with a couple of towels under your head to catch drips.
  • After 10 minutes, use the Chux to gently wipe away any softened crust from your face.
  • Then apply a thick layer of Vaseline. Use a clean teaspoon to scoop the Vaseline from the tub onto your hand, rather than

Review

Please call for a review appointment at any time if you are concerned that your reaction to treatment is not as expected.

Results following PDT can never be totally predicted, and response rates are typically 80%.

Further treatment, or surgery, may still be required in some situations at a later date. Follow-up is therefore important. If a follow-up date has not already been discussed, please clarify when you should schedule review.

What is the cost?

The cost of PDT varies according to the surface area treated. This will be discussed with you prior to treatment. Please raise any queries you may have regarding cost before the treatment is performed.

PDT is not claimable through Medicare. Some private funds may rebate a small amount of the cost. DVA patients should check whether they are covered for this treatment before proceeding.

What alternative treatments are available?

A number of prescription creams are also available to treat actinic keratoses. Efudix cream is used most commonly, and has similar efficacy rates to PDT. Efudix is less costly than PDT (one tube costs approximately $50), and is typically applied for a period of several weeks.

Who should not undergo PDT?

  • Patients who are pregnant or breastfeeding
  • Patients who are allergic to peanut (the Metvix cream may cause a reaction)
  • Patients who have porphyria (a rare disorder)
  • Patients known to have had an adverse reaction to PDT previously