Psoriasis is a chronic inflammatory skin disease, and the risk of developing cancer has been postulated due to the presence of several plausible underlying mechanisms. Understanding the association between psoriasis and cancer is imperative to the provision of optimal psoriasis care.
Objectives
To examine the risk of developing cancer in individuals with psoriasis.
Methods
Population-based cohort studies were conducted in Denmark, England, Israel, and Taiwan through the use of linked electronic health records. Individuals aged at least 18 years of age with a diagnosis of psoriasis in the country-specific study period were matched to up to 6 comparators with no record of psoriasis prior to index date. Country-specific hazard ratios for the risk of cancer development overall and for 26 site-specific cancers between individuals with and without psoriasis were calculated through Cox regression. Country-specific estimates were pooled using random effects modelling.
Results
We included 702,022 individuals with psoriasis and 4,185,342 matched comparators. In models implicitly controlled for age, sex and calendar time by matching, there was a small association between psoriasis and cancer overall (pooled HR [pHR]:1.08;95%CI, 1.04-1.13; I2= 92.4%). Adjustment for potential confounding factors resulted in a slight attenuation of risk (pHR:1.05; 95%CI, 1.01-1.09; I2=81.2%). When restricted to those with moderate-to-severe psoriasis, the risk of cancer overall was slightly higher (pHR:1.16;95%CI, 1.04-1.28; I2=92.8%) and confounder adjusted models (pHR: 1.09;95%CI, 1.03-1.15; I2=60.6%). Associations with psoriasis were present for oral cavity (pHR: 1.29; 95%CI, 1.12-1.47; I2=55.4%), pharynx (pHR:1.30;95%CI, 1.07-1.58; I2=58.4%), oesophagus (pHR:1.17;95%CI, 1.03-1.33; I2=56.6%), liver (pHR:1.53;95%CI, 1.33-1.77; I2=75.1%), pancreas (pHR:1.09;95%CI, 1.02-1.17; I2=0.0%), kidney (pHR:1.19;95%CI, 1.11-1.27; I2=0.0%), bladder (pHR: 1.13; 95%CI, 1.06-1.20; I2=28.7%), and keratinocyte cancers (pHR:1.37;95%CI, 1.16-1.63; I2=97.5%), Hodgkin lymphoma (pHR:1.56;95%CI, 1.16-2.11; I2=69.7%), non-Hodgkin lymphoma (pHR:1.16;95%CI, 1.07-1.26; I2=35.5%) and leukaemia (pHR:1.18; 95%CI, 1.08-1.29; I2=41.9%). Site-specific associations generally persisted, with slight risk exacerbations and additional associations for lung and ovarian cancers, when limited to people with moderate-to-severe psoriasis.
Conclusion
Psoriasis was associated with an increased risk of developing 14 of 26 investigated site-specific cancers, including cancers with poor prognosis, such as liver, lung, and oesophageal cancer. Our findings can be used to reinforce cancer prevention strategies in psoriasis care.
