Association Between Prurigo Nodularis and Malignancy: A Real-World Multicenter Retrospective Cohort Study

Prurigo nodularis (PN) is a chronic inflammatory skin disorder associated with various systemic disorders. However, its potential link to increased malignancy risk remains unclear. We conducted a retrospective cohort study using the US Collaborative Network in the TriNetX database, encompassing data from January 1, 2016 to January 1, 2022. Adults diagnosed with PN (n = 10 941) were matched 1:1 with controls without PN (n = 10 941) based on demographics, comorbidities, and medication use. The primary outcome was the hazard ratio (HR) for malignancy occurring between 3 months and 5 years after the index date. The HRs and 95% confidence intervals (CIs) were calculated using Cox proportional hazards models. Patients with PN exhibited a significantly increased risk of developing malignancies compared with the controls (HR 2.10; 95% CI 1.81-2.43). Notably, higher risks were observed for cutaneous squamous cell carcinoma (HR 4.24; 95% CI 2.69-6.69), basal cell carcinoma (HR 2.49; 95% CI 1.68-3.69), hematopoietic cancers (HR 1.97; 95% CI 1.26-3.06), gastrointestinal cancers (HR 1.87; 95% CI 1.24-2.81), respiratory system cancers (HR 1.86; 95% CI 1.23-2.82), and female genital cancers (HR 2.77; 95% CI 1.29-5.95). In conclusion, PN is associated with a significantly elevated risk of malignancy, particularly cutaneous cancers. These preliminary findings underscore the necessity for heightened clinical vigilance. Further prospective studies are needed to confirm this association, elucidate the underlying mechanisms, and evaluate the potential benefits of routine cancer screening in this high-risk population.