Cancer rates over a five-year period were higher in psoriasis patients than in the general population, but aren’t significantly affected by biologic drugs, according to a recent study.
Using two large patient registries, researchers compared rates of cancer diagnosis for people with psoriasis with diagnosis rates in the general population, looking at lymphoma and nonmelanoma skin cancer separately, and also at all cancers together except for nonmelanoma skin cancer. Results from the study, which were presented earlier this month at the American Academy of Dermatology meeting in Chicago, showed higher cancer rates for people with psoriasis in all three categories.
According to Alexa Kimball, one of the study authors, the findings point toward an “elevated risk” for people with psoriasis, “but it's not a huge risk.”
Researchers also analyzed cancer rates for different psoriasis treatments, but did not find a significantly greater risk associated with any particular therapy.
The study zeroed in on lymphoma and nonmelanoma skin cancer because previous research had associated a higher risk for these cancers with certain treatments, specifically tumor necrosis factor-alpha inhibitors, explained Kimball. Tumor necrosis factor-alpha (TNF-alpha) is a cytokine, or protein, involved in psoriasis inflammation. Several biologic medications, such as Humira (adaliumumab), Enbrel (etanercept) and Remicade (infliximab) work by inhibiting TNF-alpha.
Researchers found that rates of diagnosis, analyzed according to different treatments, were fairly even for all cancers except nonmelanoma skin cancer, but varied slightly for nonmelanoma skin cancer and lymphoma. Treatments analyzed included biologics, nonbiologics and phototherapy. Kimball described the data as “pretty reassuring,” noting that no one single treatment had a significantly higher rate of cancer. Rates of diagnosis were calculated in terms of 10,000 patient years of observation (PYO). Every year that each patient was studied counts as one PYO. The two registries offer information on approximately 79.3 million people, including more than 18 million people with psoriasis, according to Kimball.
In lymphoma, the incidence rate was 11.1 per 10,000 PYO, compared with 6.6 for the general population. Nonmelanoma skin cancer also had a higher incidence rate in psoriasis patients, at 147.2 for psoriasis compared with 94.2 for the general population. When looking at all cancers except for nonmelanoma skin cancer, researchers found an incidence rate of 115.5 for people with psoriasis, compared with 96 for the general population.
Kimball recommends that psoriasis patients incorporate regular cancer screenings into their routine care.
“It behooves people to think, ‘when I go get my cholesterol checked, I should make sure that I'm up to date on my cancer screens,’” Kimball said. “Know what those are, and know what you should get done.”
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