Photodynamic therapy
Photodynamic therapy is a treatment used to destroy certain superficial skin lesions, especially superficial skin cancers or precancerous lesions (actinic keratoses).
The lesions are first treated with a cream containing a photosensitizing molecule that will be preferentially captured by the pathogenic cells, then activated by a specific light source.
There are two treatment protocols for photodynamic therapy: under red light ("conventional") or under white light ("artificial daylight").
There are many benefits to this treatment:
- Efficiency
- Treatment of a large area at once
- Treatment of the entire cancer field
- Very good aesthetic result
IN practice
STEP 1 - Before the treatment:
- Get the photo-sensitizing cream at the pharmacy (prior agreement from the health insurance company). Keep it in the refrigerator, you will need to bring it with you on the day of treatment.
- In some cases, your dermatologist will ask you to apply a keratolytic cream on the area to be treated for about ten days before the treatment.
step 2 - the treatment procedure
PDT under artificial daylight
- Bring the photo-sensitizing cream with you (isothermal bag).
- A gentle curettage of the scabs is performed
- The photo-sensitizing cream is applied on the spot.
- The lamp illumination takes place after +/-20 min and lasts for 1-2 hours.
- For your own comfort, you should have something to keep you busy during the treatment but be aware that:
> for scalp treatments, protective glasses must be worn, but it is possible to read;
> for facial treatments, it is mandatory to wear occlusive eye protection. Reading is therefore not possible, but music can be played.
- After the session, a soothing and healing cream is applied directly to the treated area.
!! IMPORTANT
For PDT under artificial daylight: you need to stay on site for minimum 1h30.
PDT under red light (conventional PDT)
- Bring the photo-sensitizing cream with you (isothermal bag).
- A gentle curettage of the scabs is performed.
- The photo-sensitizing cream is applied on the spot and covered with an occultive dressing.
- You can then leave and return to the centre 2 to 3 hours later.
- The dressing is removed and the lesion(s) cleaned.
- Special opaque glasses are placed over your eyes. You will not be completely in the dark and you will be able to see a red-orange light through them, which may sometimes feel intense. This is normal and absolutely harmless.
- The lesions will then be illuminated with red light produced by LED lamps, usually for 7-8 min.
- After the session, a soothing and healing cream is applied directly to the treated area.
!! IMPORTANT
Conventional red light PDT is a two-stage treatment: an appointment is made in the morning (about 10 minutes) and then you must return to the centre 2-3 hours later (about 20 minutes).
step 3 - after the treatment:
- During the next 48 hours: avoid exposure of the treated area to daylight: cover your head, stay indoors ideally with the curtains closed, wear a mineral sunscreen outside... Indeed, there may be some residual amount of photo-sensitizing product left in the target cells that can still be activated by daylight and increase the inflammatory reaction after a standard dose.
- Redness and swelling of the lesions are common. The redness may persist after treatment, sometimes for several weeks. Crusts can occur within 10 days after the session. Even if these are important and impressive, they disappear without any side-effects. They signify the destruction of the cancerous cells.
- A soothing and healing cream should be applied daily to the treated area for several weeks, until the scabs and redness resolve. Sun protection is also recommended.
- A check-up with your dermatologist will be organized 3 months after the treatment to evaluate the result and to organize a complementary treatment if necessary.
