Survival in cancer patients hospitalized for psoriasis: a population-based cohort study in Sweden

Background Increased cancer risk after psoriasis has been observed in previous studies, whereas little is known about the prognosis in cancer patients with previously diagnosed psoriasis. Objectives We aimed at examining the cancer-specific and overall mortality among psoriatic cancer patients compared with the reference population. Methods The population-based Swedish registers were used to identify psoriatic cancer patients and cancer patients without psoriasis. We estimated hazard ratios (HRs) showing the probability of death in the two groups. Results In total, 1746 psoriatic cancer patients and 1 011 757 other cancer patients were identified from 1964 to 2006, showing a significant survival disparity [overall HR 1.27, 95% confidence interval (CI) 1.20-1.35 and cancer-specific HR 1.26, 95% CI 1.18-1.35]. An overall mortality excess after psoriasis was observed for nine cancer sites and a cancer-specific mortality excess for seven cancer sites. Stratified analyses showed that the prognosis was worse for psoriatic cancer patients diagnosed below age 65 years and for those who had been treated for alcohol-related diseases. Those with more than one hospitalization for psoriasis were more likely to be associated with an increased risk of cancer-specific mortality. Conclusions A previous diagnosis of psoriasis worsens the prognosis of many cancers. A worse prognosis was more pronounced in psoriatic cancer patients diagnosed at an earlier age, previously hospitalized for alcohol-related diseases, or with severe symptoms. Our study provides clinicians and patients with information about mortality risk and prognostic factors for psoriatic cancer patients. The mechanisms underlying this disparity warrant further studies.