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Photodynamic therapy (PDT)

The photodynamic therapy (PDT) is a method used initially to treat the non-melanoma skin tumour, basal cell carcinoma, the incidence of which decreases in the population.

Apart from surgery there are other possibilities of treating this tumour disease. Basal-cell carcinoma is a malignant skin tumour, rarely metastasising but locally destructive. It appears in older people, especially in areas exposed to sunlight – the nose, cheeks, forehead, earlobes, upper part of the trunk.

The PDT is a treatment method based on the selective photosensitivity of the tissue by means of a locally applied photosensitizer (Metvix cream) which intensifies the light sensitivity. When irradiating a focus treated with this method by visible light a cytotoxic reaction develops, which results in a tissue damage on different cell structure levels destroying the tumour focus. For the PDT red light with 635nm wavelength is used. As a source of radiation the radiator Aktilite by Galderma company is used.

The advantage of this therapy is a complete destruction of the damaged tissue without affecting normal healthy cells, which secures a good cosmetic effect. The advantages consist in its harmlessness towards the patient, an excellent cosmetic effect without scars, destruction of tumour cells without destroying the healthy tissue around. The cure success rate is in case of the basal-cell carcinoma 75%, in case of surface basal-cell carcinoma even 95%. This therapy can be used mainly in patients where surgical intervention has been contraindicated (patients with a coagulation disorder, multi-morbid patients, location surgically difficult to reach). Among the disadvantages there is the time consumption, necessity of repeating the intervention, in more sensitive patients the feeling of pain and burning sensation during the radiation (administration of analgesic premedication recommended).

The course of the photodynamic therapy

1st stage: to assure an optimum penetration of the cream into the skin it is necessary to prepare the lesion surface. We clean the skin surface with a local antiseptic and remove the skin scales and crusts with a small curette. We apply the Metvix cream by means of a wooden spatula in an even layer of 1 mm thick about 5 to 10 mm over the visible border of the lesion. Then we cover it with an impermeable foil (to enable better absorption or the cream into the skin) and at the same time a non-translucent foil (e.g. aluminium) protecting from light. Metvix cream stays there for 3 hours. One hour before the intervention patients are administered an analgesic (e.g. paracetamol) to ease the pain.

2nd stage: after three hours we remove the rests of the cream from the focus surface. Before the intervention both the personnel and the patient protect their sight with UV filter glasses.

The patient is lain on a hospital bed, in a suitable posture according to the tumour localization. The head of the machine emitting red light of 635 nm wave length is adjusted in a distance of 5–8 cm from the irradiated area. The radiation lasts according to the selected doses (J/cm2) from 8 to 10 minutes. During the radiation we can lower the temperature using the air (fan)to prevent undesirable feelings of pain and burning. In case of a higher intensity of pain we apply fraction radiation or we can extend the distance between the irradiated focus and the lamp.

After the intervention the patient is informed that erythema and edema may develop in the first three days after the intervention and possibly pustulation, crustation or even necrosis of the focus within a week after the intervention. Regarding the increased sensitivity to UV radiation the patient must use photoprotection and grease the focus with a calming cream. The treatment is repeated once per month, at least three times.

The PDT method can also be used to treat the following diseases:

Warts (Verruca vulgaris)

Procedure: Apply the 5 % ALA cream to form occlusion for three hours, then the area is irradiated for 9 minutes. High success rate after the very first irradiation. Suitable also for curing under 10 year-old children.

Solar keratosis, syn. Actinic keratosis (Keratosis actinica)

Procedure: Apply the 20 % ALA cream on the focus for 4 hours and then the area is irradiated by the lamp for 20 minutes. One radiation is usually enough. The success rate is almost 100 %.

Fungal nail infections (Onychomycosis)

Procedure: 5 days before the treatment it is necessary to apply the 40% urea gel on the affected nails once a day, then we apply the 20 % ALA for 4 hours and after that the nails are irradiated by the lamp for 20 minutes. 4 sessions are needed once in 2 weeks. The success rate is nearly 100 %.

Acne vulgaris

Procedure: After cleaning the skin apply the 5 % ALA milk to form occlusion over the acne focus for one hour, after that the area is irradiated with the lamp for 16 minutes. Three sessions are recommended at weekly intervals.