Inflammatory Manifestations, Therapeutic Interventions, and Cancer Risk in Psoriasis: Current Epidemiological and Mechanistic Evidence
Psoriasis is a chronic, autoimmune skin disease driven by persistent inflammation and immune dysfunction that severely impairs quality of life and is associated with serious comorbidities, including psoriatic arthritis, cardiovascular diseases (CVDs), and depression. Emerging epidemiological evidence suggests an association between psoriasis and an increased risk of certain malignancies, such as breast cancer (BC) and non-Hodgkin’s lymphoma (NHL), although the strength and consistency of these associations vary across study designs, and the underlying thrombo-inflammatory mechanisms remain incompletely understood. Several therapeutic approaches, including topical therapies, conventional systemic drugs (e.g., methotrexate and cyclosporine), and biological agents have been investigated for their potential associations with malignancy risk. However, the available evidence is heterogeneous and influenced by disease severity, treatment duration, cumulative exposure, and patient-related confounding factors. While some epidemiological studies have reported associations between conventional therapies and selected skin or hematological malignancies, combined or sequential treatment regimens further complicate the interpretation of treatment-related cancer risk. Similarly, Janus kinase (JAK) inhibitors have been associated with higher reported rates of lymphoma and non-melanoma skin cancer than tumor necrosis factor α inhibitors (TNFi-α) in some observational studies. Recent studies also highlight the clinical utility of inflammatory markers, specifically the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte (PLR) ratio, and systemic immune-inflammation index (SII), for monitoring systemic inflammation and treatment response, while certain therapies may additionally influence CVD risk. Despite these advances, substantial heterogeneity across observational studies, meta-analyses, and Mendelian randomization analyses preclude definitive conclusions regarding causality. Overall, this review synthesizes the current epidemiological and mechanistic evidence linking psoriasis, chronic inflammation, therapeutic interventions, cancer risk, and cardiovascular comorbidities, while highlighting the need for large prospective studies and standardized analytical approaches.