Photodynamic Therapy (PDT)

About Photodynamic therapy

Photodynamic therapy is a safe and effective non-surgical treatment for certain low risk skin cancers (e.g. superficial basal cell carcinoma and intraepidermal carcinoma/Bowen’s disease), and for precancerous lesions such as actinic keratoses (sun spots).

PDT utilises photosensitising medication, oxygen and light, to create a photochemical reaction that selectively destroys cancer cells, and minimizes injury to normal skin cells.


The main advantage of PDT is that it can eradicate the above lesions with typically excellent cosmetic result, and allows one to avoid the surgical scars that invariably result from surgical procedures. It can also avoid some of the other complications of surgery, such as the risks of infection, dehiscence and prolonged discomfort/sensation changes after surgery.

PDT treatment involves the following steps to be completed within the same day: 


  1. Attend our rooms for a 10-minute appointment to have a light-activated cream (Metvix or ALA) applied to the identified site. A skin coloured dressing will be applied to the area.
  2. There is a 3 hour (minimum) waiting period for the light-activated cream to be absorbed. You can leave our rooms during this time but you must leave the protective dressings intact. Nursing staff may advise you to take gram of paracetamol prior to returning for the illumination session.
  3. When you return to our rooms, the light-activated cream will be washed off and the site will be immediately illuminated with a red light. This light exposure usually lasts about 9 minutes.
  4. Two treatment cycles (usually around 2 weeks apart) are needed for skin cancers such as superficial basal cell carcinoma and intraepidermal carcinoma. A single cycle is usually all that is needed for precancerous lesions (actinic keratoses / sun spots).

Metvix® PDF treatment procedure

Then REPEAT 1-4 weeks later for superficial basal cell carcinoma and intraepidermal carcinoma.

Side Effects

Due to the non-invasive and selective nature of the treatment, the potential for scarring and side effects are minimised, however some pain & redness of the area may occur. Within a few days, the exposed skin and BCC will scab over and flake away.

Short term side effects may include:


  • Pain (common): Usually mild burning sensation – sometimes more intense. Local anaesthetic can be used. Pain is usually much shorter duration and less severe than for surgery.
  • Redness (common): Usually lasts up to a few weeks; rarely, it can be long lasting.
  • Swelling (common): Usually lasts several days.
  • Pustules (common): Tiny white pustules are common, and are not an indication of infection. These disappear over several days.
  • Blistering (uncommon).
  • Ulceration (uncommon).
  • Infection (rare). 

Medium to longer-term side effects may include:


  • Hyperpigmentation (common): The skin in the treated site may be darker than the surrounding skin (like an area of dark tan) for several months. It usually settles spontaneously, and can be improved faster with fading creams if needed.
  • Hypopigmentation (uncommon): The treated area may be paler than the surrounding skin.
  • Scarring (rare): True scarring is rare. There may however be a tiny scar from the biopsy done to diagnose the lesion.

After Care

Minimal aftercare is needed. Simple analgesia (e.g. paracetamol) may help with the minor discomfort. An ointment such as Vaseline or white soft paraffin can help speed skin healing.

Photodynamic therapy for superficial basal cell carcinoma (sBCC) and intraepidermal carcinoma (IEC)

Studies have shown that PDT can give cure rates of 85% to 90% for appropriately selected superficial BCC (sBCC) and intraepidermal carcinoma (IEC/SCC in situ/Bowen’s disease). Nodular BCC are less responsive to PDT, but can be treated in appropriate circumstances.


PDT is not suitable for melanoma or squamous cell carcinoma, or higher risk BCC (e.g. morpheic, sclerosing, micronodular), recurrent BCC (lesions which have recurred after previous treatment), or thick BCC (lesions greater than 2mm in depth).


A skin biopsy is usually recommended prior to treating lesions to confirm the diagnosis and to make sure the lesion is of correct subtype to respond to the treatment.

PDT for Actinic keratoses (AK)

Actinic keratoses (sunspots) are pre-cancerous lesions. Whilst mild lesions are sometimes observed, more advanced lesions are usually treated. A small percentage of actinic keratoses progress to squamous cell carcinoma (a potentially very dangerous skin cancer which requires surgery). Actinic keratoses are also often cosmetically obvious, scaly and irritable, and thus benefit from treatment.


Actinic keratoses usually occur in a field of solar damage, with clinically visible lesions combined with subclinical lesions (not readily visible). Field treatment may be suggested. Suitable field treatments include topical creams (5-fluorouracil, imiquimod, ingenol mebutate), and PDT.


A Follow up appointment is usually made 3 months post treatment to check the effectiveness of the procedure. Late recurrence is possible, so a check yearly for a few years is also advised. Also, if you have developed one skin cancer there is a high risk (perhaps 40%) of developing further skin cancers elsewhere on your skin in the future. Regular skin checks are helpful. Sun protection and sun avoidance can reduce the risk of future skin cancer.

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