Risk of lymphohematologic malignancies in patients with chronic plaque psoriasis: A systematic review with meta-analysis

Background: The association between chronic plaque psoriasis and lymphohematologic malignancies (LHMs) remains controversial. Objective: To investigate the risk of LHMs in patients with psoriasis according to the best evidence. Methods: A systematic review and meta-analysis of observational cohort studies was undertaken to assess the association of psoriasis with different LHMs. A literature search for relevant studies was performed on February 28, 2021. The random-effects model in conducting meta-analyses was applied. To evaluate the risk of bias, the Newcastle-Ottawa Scale was employed. Results: A total of 25 observational studies were selected, comprising collectively 2,501,652 subjects. A significantly increased risk for LHM (hazard ratio [HR], 1.55; 1.24-2.94) and lymphoma (HR, 1.27; 1.08-1.50) in patients with moderate-to-severe plaque psoriasis compared to the general population was found. In detail, increased risks for Hodgkin lymphoma (HR, 1.71; 1.27-2.30), non-Hodgkin lymphoma (HR, 1.27; 1.08-1.50), multiple myeloma (HR, 1.32; 1.03-1.69), and leukemia (HR, 1.28; 1.00-1.65) were found. The risk of cutaneous T-cell lymphoma was markedly augmented in patients with psoriasis (HR, 6.22; 3.39-11.42). Limitations: Possible ascertainment bias related to the diagnosis of LHMs. Conclusion: The increased risk of LHMs, particularly cutaneous T-cell lymphoma, in patients with psoriasis could be related to exposure to systemic immunosuppressive therapies, comorbidities, and sustained immune activation, particularly in the skin.