Out of the estimated 125 million individuals suffering from psoriasis worldwide, many may be capable of sufficiently managing the condition with the use of topical prescriptions alone. However, in the case of nearly 25% of patients these methods do not suffice – often, disease severity necessitates alternative options, including systemic and biologic treatments. These interventions are often accompanied by systemic adverse effects and immunosuppression, however, other forms of treatment may serve as reasonable and efficacious options for patients requiring more than topical medications to manage their symptoms.
Phototherapy has proven to be a successful treatment option for such psoriatic patients as it works to reduce skin inflammation and reduce skin cell production. For patients with moderate-to-severe psoriasis, phototherapy may be the most highly recommended treatment and is often utilized due to its limited side effects. As the use of the modality increases, experts have updated the guidelines for phototherapy treatment to ensure safety, appropriate use, and optimal patient outcomes. In partnership with the National Psoriasis Foundation, the American Academy of Dermatology recently released new guidelines on the management and treatment of psoriasis with different types of phototherapy.
Narrowband Ultraviolet B Phototherapy
Narrowband ultraviolet B therapy refers to the use of wavelengths ranging from 311 to 313 nm, and it is generally recommended for the treatment of plaque psoriasis in adults. The starting dose for NB-UVB therapy should be based on skin-phototype protocols or the minimal erythema dose (MED). For adults with generalized plaque psoriasis, the frequency of treatment can range between twice and thrice weekly; a frequency higher than that has little beneficial effects and may instead expose the patient to higher doses of UVB radiation unnecessarily. Maintenance treatment sessions, on the other hand, may be performed once weekly after improvement or skin clearance has been achieved.
NB-UVB therapy is recommended over both broadband ultraviolet B monotherapy and PUVA therapy due to its higher safety profile and better demonstrated results. For appropriate patients with generalized plaque psoriasis, NB-UVB phototherapy may be used in a home setting as an alternative to in-office treatments.
To potentially improve the efficacy of treatment, NB-UVB may be safely augmented with concomitant topical therapy, including retinoids, vitamin D analogues, and corticosteroids. In appropriate patients with generalized plaque psoriasis, NB-UVB may be combined with oral retinoids if the response to monotherapy is insufficient. Additionally, the use of apremilast may be useful as an adjunctive therapy in appropriate patients.
Due to the increased risk of skin cancer development, the long-term use of cyclosporine in combination with NB-UVB is not recommended. Caution should be maintained when administering phototherapy to patients with a history of melanoma or several non-melanoma skin cancers, arsenic intake, or prior exposure to ionizing radiation due to the risk of photocarcinogenesis.
BB-UVB phototherapy utilizes wavelengths ranging from 270 to 390 nm, with peak emission at 313 nm. It is an older type of phototherapy and carries many adverse effects – especially when compared with NB-UVB treatments. For adult patients with generalized plaque psoriasis, BB-UVB is recommended if NB-UVB is unavailable as it is less effective than either NB-UVB or oral PUVA monotherapy. However, monotherapy with BB-UVB may be considered for adults with guttate psoriasis. Additionally, BB-UVB and acitretin combination therapy may be considered in adults with generalized plaque psoriasis when appropriate.
Similar precautions should be taken as in the case of NB-UVB therapy when treating patients to protect them from increased skin cancer risk.
Targeted UVB Phototherapy
Recommended for the treatment of localized psoriatic lesions – affected areas less than 10% of body surface area – targeted UVB phototherapy includes excimer laser and light therapies (both at 308 nm), as well as targeted NB-UVB light at wavelengths between 311 and 313 nm. One of the main advantages of this type of phototherapy is its ability to target only affected areas, sparing surrounding skin, and also permitting higher doses, faster clearing, and lessening associated risks. To achieve optimal results, targeted UVB therapy should be administered 2-3 times per week. The initial dose of the treatment should be based on the minimal erythema dose, fixed-dose, or skin-phototype protocol.
The most efficacious UVB phototherapy for localized plaque psoriasis in adults is the excimer 308-nm laser, which is also the recommended method for adults with scalp psoriasis. Second is the excimer 308-nm light, followed by localized NB-UVB 311- to 312-nm light. The recommended targeted UVB treatment for adults with plaque psoriasis – as well as those with palmoplantar psoriasis – includes both excimer 308-nm laser and 308-nm light. The excimer 308-nm laser treatment may be used in combination with topical steroids when required.
PUVA therapy relies on the use of psoralens as photosensitizing agents to sensitize target cells to the effects of UVA light in order to effectively treat psoriasis as well as other dermatologic conditions. Psoralens, which may be either synthetic or naturally occurring, can be administered topically in cream form or mixed with bath water, or they can be taken orally.
Topical PUVA therapy has been deemed superior to NB-UVB 311- to 313-nm light for the treatment of localized plaque psoriasis in adults – in particular palmoplantar and palmoplantar pustular psoriasis. Oral PUVA is the recommended treatment modality for mild psoriasis in adults, while bath PUVA is suggested for adults with moderate-to-severe psoriasis.
Similarly to PUVA, photodynamic therapy utilizes photosensitizing agents to target designated cells. In the case of photodynamic treatment, the chemicals destroy premalignant or malignant cells. According to the latest clinical guidelines, photodynamic therapy with either aminolevulinic acid or methyl aminolevulinate is not recommended for adults with localized psoriasis – including both palmoplantar and nail psoriasis.
Grenz Ray, Climatotherapy, and Other Phototherapy Methods
There exists a plethora of additional phototherapy methods, including climatotherapy, grenz ray, visible light, Gockerman, and pulsed-dye laser therapies. However, evidence is currently insufficient to recommend grenz ray or visible light phototherapy for the treatment of psoriasis. Sufficient evidence has been found to recommend climatotherapy and Gockerman therapy – coal tar combination with UVB light – for the treatment of psoriasis. Additionally, pulsed-dye laser has been suggested for the treatment of nail psoriasis. The lesser-known therapies should be recommended and administered with caution.
Alongside the latest clinical recommendations, physicians should also take into account patient preferences to ensure post-treatment satisfaction. The efficacy and safety profiles of each recommended phototherapy method should be discussed with patients thoroughly, to ensure they make an educated decision regarding their preferred therapy. In addition, patients should be made aware of dosing frequency, price, accessibility, and availability – all of which may influence their decision. While the maximum dose of phototherapy should never be exceeded, some patients may opt to extend treatment duration in favor of less frequent therapy dosing for the sake of convenience.