PUVAthérapie et cancers cutanés

Cutaneous Carcinogenic Risk of Phototherapy: An Updated Comprehensive Review

Phototherapy is among the oldest and most highly effective treatment modalities available for moderate-to-severe psoriasis. However, concern regarding the potential carcinogenic risk associated with ultraviolet B (UVB) phototherapy and/or psoralen with ultraviolet A (PUVA) has been expressed by both providers and patients. The purpose of this review is to assess the cutaneous malignancy risks of UVB phototherapy and/or PUVA in all skin types, including Caucasian and non-Caucasian patients. We searched the MEDLINE database for original research articles regarding the skin cancer risk of phototherapy. A total of 61 articles were included. In Caucasians, an increased risk of squamous cell carcinoma with PUVA therapy was reported after >250 sessions, whereas studies among non-Caucasians did not show any increased risk. There was no convincing evidence of increased skin cancer risk associated with UVB phototherapy among all skin types. In view of the continued validation of its safety, phototherapy remains a valuable treatment option for patients with moderate-to-severe psoriasis.

[Phototherapy and carcinogenesis]

Phototherapy successfully uses the short-term effects of ultraviolet light against inflammation and proliferation. For its long-term effects, however, ultraviolet light was recently classified as a carcinogen. The wave spectrum employed in phototherapy has various carcinogenic effects in experimental systems, most notably DNA mutations in keratinocytes. Clinically, PUVA increases the risk for squamous cell carcinoma of the skin, especially after following 350 or more phototherapy sessions over a lifetime. Melanoma and genital skin cancer are not increased by PUVA alone. Previous UV damage, immunosuppression and other systemic treatments increase cutaneous carcinogenesis through PUVA. In contrast, broad-band UVB, narrow-band UVB and UVA1 have not yet been linked to cutaneous carcinogenesis, but will need careful follow-up in larger studies. Phototherapy remains a safe treatment modality, provided that the indication is well-founded, previous exposure and co-carcinogens are considered, and short and dose-intensive treatment protocols are favored, PUVA is chosen as second-line treatment that should not be used for more than a lifetime total of 250-300 phototherapy sessions.

The treatment of severe atopic dermatitis in childhood with narrowband ultraviolet B phototherapy

BACKGROUND

There is a lack of data regarding the use of narrowband ultraviolet B (NB-UVB) phototherapy in children with atopic dermatitis (AD). Many centres use this mode of treatment for children with AD; however, there have only been two previous studies observing the effect of NB-UVB in children with AD.

AIM

We undertook a retrospective review of children with severe eczema who had undergone NB-UVB consecutively in our department between 1999 and 2005.

METHODS

All children with AD who had undergone NB-UVB consecutively in our department between 1999 and 2005 were identified from the phototherapy database. Their clinical notes were reviewed for information on age, sex, skin type, minimal erythema dose (MED), adjuvant therapy, previous therapy, adverse effects, number of exposures, cumulative dose, response to treatment and length of remission.

RESULTS

In total, 50 children (83%) completed more than 10 exposures of NB-UVB. Complete clearance or minimal residual activity was achieved in 20 children (40%). A good improvement was achieved in a further 10 children (23%), and a moderate improvement in 13 (26%). Children with MEDs > 390 mJ/cm2 were more likely to clear, and this was found to be statistically significant (P = 0.02). Overall, the treatment was well tolerated and the median length of remission was 3 months.

CONCLUSION

NB-UVB is an effective treatment for children with severe AD. Children with MEDs > 390 mJ/cm2 are more likely to clear. Further studies are needed to evaluate the efficacy of NB-UVB and long-term safety in treating children with severe AD.

Ultraviolet light phototherapy for allergic rhinitis

Phototherapy has a profound immunosuppressive effect and is widely used for the treatment of immune mediated skin diseases. Phototherapy is able to inhibit immediate type hypersensitivity reaction in the skin. Intranasal phototherapy is a new approach for treatment of allergic rhinitis. In two open studies, 308 nm excimer laser and topical PUVA therapy efficiently inhibited clinical symptoms of allergic rhinitis. In a randomized, double-blind study combined low dose UVB, low dose UVA and visible light proved to be effective in reducing symptom scores for sneezing, rhinorrhea, nasal itching and the total nasal score in ragweed allergic patients. Mechanism of action of phototherapy is complex, it reduces the antigen presenting capacity of dendritic cells, induces apoptosis of immune cells and inhibits synthesis and release of pro-inflammatory mediator from several cell types. Therefore, intranasal phototherapy may represent an alternative treatment of allergic rhinitis and other inflammatory and immune mediated mucosal diseases.