Photodynamic Therapy – PDT

Photodynamic Therapy PDT At A Glance

  • Best Results1-2 treatments
  • Treatment Recovery2 - 5 days
  • Procedure Time45-120 min
  • Skin SpecialistDavin Lim
  • Duration of Results2-7 years
  • AnaestheticNumbing, blocks
  • Back to Work1-5 days
  • Cost$$

Photodynamic Therapy - PDT

Photodynamic therapy or PDT is a procedure that uses light sensitive chemicals and low-level lasers / Light Emitting Diodes. This treatment can provide limited photo rejuvenation. It is best employed to treat superficial skin cancers, sun damage & sunspots – solar keratosis. I frequently use a combination of fractional lasers & PDT as this combination addresses both pigmentation & cellular damage. Downtime following this procedure ranges between 2 to 5 days.

FactsFacts on PDT / Photodynamic Therapy

  • Sun damage can present in many ways including brown liver spots, premature wrinkling, as well as rough dry red and scaly areas on the forehead, nose, cheeks and temples
  • The most common form of sunspots are solar keratosis or actinic keratosis 
  • These sunspots are precancerous and should be treated
  • Treatment of background sun damage will enable a Specialist to pick up any cancers at an earlier stage
  • PDT combines a light sensitive chemical with radiation of light to destroy abnormal skin cells
  • PDT can be effective in treating superficial skin cancers & sun damage, in addition to providing photo rejuvenation 

What is PDT or photodynamic therapy?

Photodynamic therapy or PDT is a treatment performed by dermatologists. It uses light sensitive agents combined with oxygen & specific wavelengths of light. This gives a photochemical reaction in the skin killing precancerous & cancerous cells.

PDT is best used for specific management of skin cancers or pre-cancer. It is over-rated for cosmetic indications & is even more over-rated for treating acne (both traditional PDT & the super-expensive Kleresca). Read more to understand.

What skin conditions can be treated with PDT?

PDT is best for treating superficial skin cancers such as basal cell carcinomas, & thin squamous cell cancers known as in-situ SCC/Bowen disease. PDT can also be used to treat sunspots in the form of solar keratosis

The conditions listed below can also be treated with PDT, however there are better, more effective treatment available-

  • Skin rejuvenation: overrated, lasers do a much better job
  • Acne: simple creams & peels are more effective in the long run
  • Seborrhoea or oily skin; a vitamin A tablet twice a week does a better job
  • Sebaceous hyperplasia: lasers offer better results & clearance
  • Rosacea: often flares up with PDT, a very small percentage of patients improve

What are the PROS & CONS of PDT?

PDT can be highly effective in the treatment of some forms of skin cancer. Advantages of this treatment include-

PROS

  • Precision targeting of lesions
  • Less invasive than traditional surgical procedure
  • Quick often outpatient treatment
  • No long-term side effect
  • Excellent cure rate when used correctly
  • Minimal scarring post treatment
  • Can be repeated on the same sites
  • Relatively cost effective

 

CONS

  • PDT only treats superficial skin cancers
  • Long term clearance of sun damage is not as good compared to some other treatments
  • Relatively expensive compared to cryotherapy (freezing)
  • Contraindicated in some forms of blood disorders

How is PDT performed?

There are two ways to perform PDT. Firstly (as described below) is in-clinic application, & secondly (as described later) is at home DIY daylight PDT

In-clinic PDT is for the management of skin cancers supervised by specialist dermatologists. The process goes something like this-

Step 1: A photosensitising cream is applied to the lesion. To increase absorption of light, some lesion skin may be scraped off prior to application. A comfortable clinic area is provided while the agent is absorbed over a period of 2-3 hours. This allows the cream to be concentrated in the cancer cells.

Step 2: The cream is removed & red light is then delivered over 7 minutes & 30 seconds. The treatment area needs to be protected from light exposure during recovery for at least 48 hours. In some cases, additional treatments are administered during the following weeks or months.

Step 3: The area of treated skin will have some redness, stinging, & peeling. This is entirely normal.

For cases of superficial skin cancers, your dermatologist will arrange a second session 2-12 weeks from the initial. For sun spots, solar keratosis & photo rejuvenation, only one session is required.

Davin’s Viewpoint on PDT

This is a useful treatment for some forms of skin cancer including low risk basal & superficial SCC in-situ. This especially applies to more cosmetically sensitive sites including the face, chest & decolletage areas. Lesion prep will differ between dermatologists. For younger patients I do not aggressively curette the lesion as this will leave skin colour changes that are often permanent. It is important to note that PDT is only suitable for select cancers. Deeper cancers will require excision.

In the context of field treatments, namely treating the whole (or part) of the face, my main prescription for PDT is daylight PDT as this is more convenient, much less painful & still effective for patients. Though the literature suggest good clearance with daylight PDT, my experience over the past 20 years does not reflect the findings. I prefer a combination of lasers & PDT or high density thulium laser resurfacing over PDT alone.

Lasers offer many advantages over PDT, including the ability to treat dyschromia, namly brown spots & dots (lentigos, pigmented solar keratosis, macular seb keratosis & freckles). Lasers also address solar dysplasia, namely UV induced DNA damage to keratinocytes or skin cells. In the context of comparing PDT to lasers, the latter is also more cost effective, less painful (in the context of illumination), & is associated with a quicker recovery time.

In the context of acne, this procedure has been commercialised by mainstream clinics. The treatment of course is Kleresca. This is essentially PDT that has been marketed to the maximum. The photosensitiser is a porphyrin, the illumination is with blue light, using two spectrums. It can work, but recurrence is the rule. I am very selective as to who I treat (or advice) with Kleresca treatment as this protocol is very expensive.

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