Treatment of psoriasis is step by step:
- The base and most important is education and support
- Then comes topical treatment
- Then comes systemic treatment and/or phototherapy
Does UVB (Ultraviolet type B) have a role to play in the treatment in psoriasis?
- US Survey on 387 dermatologists and asked what treatment they would use as first line therapy:
“Healthy adults with 10% BSA (Body Surface Area affected) not working on topicals and health affected”
- UVB was answered as the first line therapy in 40% in men up to 60% in women. The difference is because use of methotrexate and retinoids is risky in women of childbearing age.
- Phototherapy is therefore still the champion for clinicians !
What is the most effective treatment: systemic treatment or phototherapy ?
- Study done in 713 patients from 10 medical centers
…with moderate to severe psoriasis
…on monotherapy (using one treatment)
- Out of the patients: the following proportion were “Clear or almost clear” with:
- Methotrexate (MTX): 23.8% of cases
- Adalimumab: in 47.7% of cases
- Ustekimumab and Etanercept in around 30% of cases
- Phototherapy: in 26% of cases.
- Phototherapy appears slightly less effective than the other biologics. However, there is a huge cost difference. UVB is cost effective. With one year of treatment with biologics, one can buy one phototherapy machine !
How does phototherapy work in psoriasis?
- It is somewhat still speculative
- It acts on keratinocyte hyperproliferation and immune activation
- UVB action on immune activation:
- Induces apoptosis of activated T cells
- Induction of T-regulatory cells
- UVB action on keratinocyte hyperproliferation
- UVB radiation on the epidermis induces also apoptosis of epidermal keratinocytes.
- On biopsy: staining with caspase-3 is positive and thus shows apoptosis.
Dangers of phototherapy in psoriasis
- UVB is a complete carcinogen and causes carcinogenesis in mice at high dosage
- However in psoriasis:
- PUVA (psoralen + ultraviolet A) causes 30 times increased incidence of SCC (Squamous Cell Carcinoma) and 5 times more of BCC (Basal Cell Carcinoma)
- 2/3 of the SCCs are located on the lower limbs
- 150 and 350 treatments are thresholds for heightened risk of skin cancer
- NBUVB (narrowband) is safer as it only uses on wavelength (311nm)
Source of Information: Lui H, Phototherapy Update. Dubai World Dermatology & Laser Conference & Exhibition – Dubai Derma 13 – Dubai, United Arab Emirates (UAE)
Source of information: here