Skin Cancer & Sun Spot
Before treatment -> 3 Months after treatment
PDT may be used to treat large area Actinic Keratosis lesions on the face, scalp and body or individual non-melanoma skin cancers such as Basal Cell Carcinomas.
Patient undergoing PDT treatment
3 Days post treatment
6 Weeks after PDT scalp
PDT for BCC’s
When treating individual BCC’s or actinic keratoses, photodynamic therapy (PDT) is a 2-step procedure involving the application of a photosensitizing cream , Methyl Aminolevulinate (Metvix), to the cancerous lesion before exposing it to a 630nm red light source. “This light promotes selective destruction of abnormal cancerous cells while sparing any damage to adjacent healthy structures. In fact there is a photorejuvenation effect on normal skin – explained Dr Seit
Not all types of BCC’s are suitable for this treatment. If the tumour is deeply infiltrating or a morphoeic type, then surgery remains the treatment of choice. Photodynamic therapy is suitable for superficial & nodular Basal Cell Carcinomas when surgery is considered inappropriate. Patients with multiple lesions or has a BCC in a cosmetically sensitive area would also benefit from this treatment.
This novel treatment involves the topical application by the treating doctor/nurse of a photosensitiser called methyl-aminolevulinic acid (Metvix cream) to the BCC, followed 3 hours later with exposure of the treatment area of skin with a red light source for 8 minutes at 630 nm. The treatment is repeated 7 days later.
Metvix works by penetrating the stratum corneum into tumors, including basal cell carcinomas, in-situ-squamous cell carcinomas and solar keratoses, as well as sebaceous glands. There, it can be transformed into a highly photoactive endogenous porphyrin derivative, protoporphyrin IX (PpIX). Red or blue light sources can activate PpIX, which destroys cells by generating singlet oxygen molecules.
Effects of the treatment include a mild burning or stinging sensation followed by local reddness, mild swelling and subsequent crusting – similar to the range of reactions experienced with short liquid nitrogen cryotherapy. The area heals up with a good to excellent cosmetic result compared with conventional treatments over a period of 2-6 weeks and the clearance rate of many basal cell carcinomas using PDT is reputed to be as good, or better, than the clearance rate for conventional non-surgical techniques such as cryotherapy. The cure rate for PDT compares favourably with conventional surgery (>90% for superficial BCC’s and >75% for nodular BCC’s).
The biggest advantages of PDT is that there is minimal or no scarring associated with the treatment. In addition, treatment compliance is assured with PDT as the patient only has to come twice for a treatments with little at home hassles.. Furthermore, patients have less treatment related anxiety, less downtime from work, sport and other activities. There is a low risk of infection following PDT.
Most patients are suitable for Photodynamic Therapy, however there are some contraindications and precautions in which some patients may not be suitable for PDT. This is to be discussed with the doctor when deciding the treatment.
PDT for Actinic Keratoses
When treating large areas of skin affected by large numbers of actinic keratoses (eg whole face), topical 20% 5-aminolevulinic acid (5-ALA) solution is applied to the whole area by the nurse or physician. This is converted into an endogenous photosensitiser once absorbed into the skin. It concentrates around cells with rapid cell turnover such as cancerous cells, pre-cancerous cells and sebaceous glands. 1 to 3 hours later, medicated areas are exposed to strong red light, which activates the 5-ALA. The treatment selectively destroys actinic keratoses, causing little damage to surrounding normal skin, although some swelling often occurs.