CHICAGO – Malignancy rates in patients with psoriasis outstrip those in the general population, based on data from a retrospective analysis of commercial claims.
Rates for all cancers were similar among patients undergoing different psoriasis treatments, with the exception of nonmelanoma skin cancer and lymphoma.
Dr. Alexa B. Kimball
Rates for these two cancers were more variable across treatment groups, but were still above those in the general public, Dr. Alexa B. Kimball reported at the American Academy of Dermatology summer meeting.
The increased cancer risk may be associated with chronic inflammation, a hallmark of psoriasis, and exposure to some psoriasis therapies such as phototherapy with psoralen plus ultraviolet, cyclosporine, and methotrexate, she noted in the study’s background information.
Previous studies also have suggested that patients with psoriasis may be at increased risk for some cancers such as respiratory tract, urinary tract, and liver cancers, non-Hodgkin’s lymphoma, and skin cancers.
To evaluate the incidence of malignancy, the investigators obtained data from the MarketScan Commercial and Medicare Supplemental claims databases for patients with a diagnosis of psoriasis on or before Dec. 31, 2006, and at least one prescription claim for etanercept (Enbrel), adalimumab (Humira), infliximab (Remicade), ustekinumab (Stelara), nonbiologic therapies, or phototherapy.
The general population cohort included patients at least 18 years old as of 2005 or at enrollment in the health care plan. Both cohorts had 12 months’ continuous enrollment in the health care plan from Jan. 1, 2005, through Dec. 31, 2006.
Follow-up for a patient ended at the first cancer event, disenrollment from the health care plan, or after 5 years from the index date.
Patients with psoriasis had a 5-year malignancy rate of 115.5 cases/10,000 person-years, compared with 96/10,000 person-years for the general population, reported Dr. Kimball of Massachusetts General Hospital, Boston.
Excluding nonmelanoma skin cancer and lymphoma, incidence rates were similar across treatment groups: etanercept (100.2/10,000), adalimumab (94.6/10,000), infliximab (138.1/10,000), ustekinumab (100.6/10,000), nonbiologics (116.8/10,000), and phototherapy (117.3/10,000).
"These large database queries continue to be reassuring that most systemic therapies are not changing the risk for common cancers, excluding lymphoma and skin cancer, which we continue to examine separately," Dr. Kimball said in an interview.
Nonmelanoma skin cancer was far and away the most common malignancy in psoriasis patients, occurring at a rate of 147.2/10,000 person-years vs. 94.2/10,000 person-years among the general public. Rates were highest in patients treated with adalimumab (234.2/10,000 person-years) and ustekinumab (233.3/10,000) and lowest in those treated with etanercept (155.9/10,000).
"Even with the large size of the database, the number of skin cancers remains small, so making conclusions about specific therapies may be premature," she said.
Incidence rates of lymphoma were considerably lower, but again higher in psoriasis patients than the general public (11.1/10,000 vs. 6.6/10,000). Rates of this hematologic cancer were highest with ustekinumab (25.1/10,000) and, once again, lowest with etanercept (6.9/10,000), according to the poster.
In all, 5,857 patients received nonbiologic therapies, 6,856 received etanercept, 3,314 adalimumab, 1,044 infliximab, 526 ustekinumab, and 5,156 were treated with phototherapy.
Dr. Kimball is a consultant for several pharmaceutical companies including Amgen, the study sponsor.