Phototherapy: a ‘giant first step’ for patients with severe psoriasis

Ultraviolet light-based therapy, or phototherapy, has been around for nearly 70 years and is an effective treatment option for patients with psoriasis.

Susan E. Katz, MD

With narrowband ultraviolet B (UVB) therapy, about 70% of patients with psoriasis can achieve a 75% reduction in their Psoriasis Area and Severity (PASI) score from baseline, Susan E. Katz, MD, clinical assistant professor in the Ronald O. Perelman Department of Dermatology at NYU Langone Health, told Healio during an interview.

It can take about 24 treatments to see positive results, according to Katz, but a dermatologist can judge if a patient is beginning to turn the corner after about 12 to 18 treatments.

“Phototherapy is wonderful because it’s one of the few treatments that we could actually say is remittive,” she said. “Meaning that after people achieve clearing, they may stay clear for very long periods and there are some patients who may have to do light maybe once a year to stay relatively clear. It is also a very safe treatment.”

Before phototherapy existed, methotrexate was the only option for effective treatment, according to Katz. Currently, the effectiveness of phototherapy has been overlooked in part due to the tremendous advances with biologics, she said.

Risk for skin cancer

Although light therapy can have side effects, Katz said that its safety is greater than treatments of similar efficacy for psoriasis, such as methotrexate and biologicals. It does not share their potential for organ toxicity, infection or carcinogen.

Clinicians should advise patients about the increased risk of photo-aging and skin cancer (especially on the lower extremities) as well as monitor the heat within the box; Katz cautioned that it is important to select properly for patients. She also noted that the risk for side effects does not change with the severity of a patient’s psoriasis.

“The skin cancer risk is more of an issue in some ways now than it was before, because many patients may have a history of more sun exposure prior than maybe previous generations, and may also be exposed down the road to biological that may promote skin cancer” she said.

Katz also discussed psoralen and ultraviolet A (PUVA), an older form of phototherapy often combined with medication. Though PUVA was effective and a faster therapy than narrowband, Katz stated the risk for skin cancer was greater.

“There are some people who had PUVA in the past who may have more photodamage to their skin and be at greater risk,” she said.

“We sometimes forget that there’s a certain perspective on efficacy and side effects that cannot be achieved until you have a distance of some decades from the treatment. There’s sometimes great latency between the insult and then the subsequent development of the complication,” Katz told Healio. “I can tell when a patient comes in if they’ve had PUVA in the past. It’s all over their skin, I know what their complications are and I’m immediately looking at their legs because of the development of cancers. Hopefully we will never see something like that again.”

Narrowband UVB

At this point, Katz believes narrowband UVB has proven itself as a safe therapy and she uses it in her practice. She also discussed targeted treatment using an excimer laser, which she said was a good treatment with the limitation that it can only be used for localized disease. For small areas, it can clear people faster than with conventional therapy, she added.

The effectiveness of narrowband UVB therapy for psoriasis prompted the release of joint guidelines from the American Academy of Dermatology and the National Psoriasis Foundation on the risks and benefits of this treatment.

“The guidelines are somewhat general, but I think that for practitioners who are using light who may be outside of an academic center, it’s very helpful for them to have a general guideline, both in terms of the different light sources that they can use or recommend to patients and how to dose patients,” Katz said.

In the guidelines, experts recommended narrowband UVB treatment two or three times a week, also warning that a greater frequency results in minimal benefit and may expose a patient to a higher total dose of UVB radiation, which can lead to a greater risk for UV-induced erythema. They advised that a thin layer of emollient should be applied before treatment to increase effectiveness and reduce erythema. Home narrowband UVB units can be considered, according to the guidelines.

“Oftentimes without published guidelines, there’s a lot of variation in how patients are dosed, which is not useful to patients,” Katz said. “For practitioners, it’s not only important that people be able to compare passing scores across different kinds of phototherapy, but to compare with non-phototherapy modalities. When you see in black and white that you can clear someone with light as well as you can with some biologics, if you were not aware that, then this is an eye opener for you.”

Challenges to light, future research directions

Although light therapy is effective for psoriasis, there are “serious, serious roadblocks,” Katz stressed, including both financial and time commitment barriers.

The reimbursement for light therapy is moderately low and patients are expected to come in for therapy two to three times per week for at least 8 to 12 weeks, according to Katz. Also, insurers may not always cover a visit and a light treatment on the same day. Many offices do not offer either narrowband or excimer laser because it’s not economically feasible, she added.

“As a dermatologist, you need to be able to afford to offer light to patients,” she told Healio. “You have to dedicate part of your real estate to a light box and you have to dedicate your staff to light therapy. You have them assisting and delivering light. You need people who are properly certified and trained, you need to be able to offer light to enough patients to pay for that real estate.”

However, Katz also said that the overall cost of phototherapy is “much less than the cost of any of the biologics.”

“Years ago, the insurers would create potentially a package for light treatment and the patients were not subjected to a copay each visit. As it has happened, in many instances, the insurers now are passing on much more of the cost directly to the patient,” Katz said. “This is a severe limitation, so it’s hard for patients to find phototherapy units near them and to find doctors who are skilled in doing it outside of some private practices and university settings. This is probably one of the biggest problems.”

Economic research is needed that show these challenges, Katz said.

“I would love to see economic studies that essentially force the hand of perhaps the insurers to restructure the way in which they cover this very valuable and safe treatment for patients,” she said. “We’re talking about great cost savings to everyone. That really is a concern.”

Future research should also examine new light sources and applications of existing light sources that may not currently be used readily– like pulsed dye light, more sophisticated units and units for home settings with greater remote supervision from physicians, according to Katz.

The doctor-patient relationship

Newly diagnosed patients with psoriasis and patients with severe disease treated in some community settings are not always aware of the treatments available to them, Katz said. There are also patients who may have only received topical medication in the past and never any systemics, like methotrexate, acitretin or cyclosporine, or a biologic.

“When they come into your office, you’re going to have to start at square one and discuss not only the nature of their condition, but all the modalities that can be used,” Katz said. “I will always, when it is appropriate, suggest someone consider light first before they necessarily go on to internal medication.”

Katz emphasized that it’s rewarding to treat patients with psoriasis using phototherapy not only because they are grateful for the positive results it can bring, but because the frequent visits allow an opportunity to develop a patient-doctor relationship that’s not always seen in dermatology.

“It’s one of the nice human touches to this approach, but of course, it’s not the reason we do this,” she said. “We do this treatment, because it is effective, it is safe and it is often the giant first step for the patient with severe disease as they enter the world of therapeutic opportunity for them. But it does cement your relationship with the patient and it's a lovely thing.”

References

• Elmets CA, et al. J Am Acad Dermatol. 2019;doi:10.1016/j.jaad.2019.04.042.
• National Psoriasis Foundation. Phototherapy fact sheet.
  https://www.psoriasis.org/sites/default/files/phototherapy_fact_sheet_0.pdf Accessed on Feb. 20, 2020.