Risks of malignancies among patients with psoriasis: A cohort study of 360 patients

Psoriasis is a systemic, chronic, immunologically-mediated disease affecting approximately 2%-4% of the worldwide population. It is well known that psoriasis is associated with several comorbidities such as metabolic syndrome, cardiovascular disease, and malignancy. Although meta-analyses and large prospective cohort studies have shown an increased risk of malignancies in patients with psoriasis worldwide, an association between psoriasis and malignancy onset has not yet been established in Japan. We retrospectively analyzed 360 patients with psoriasis at our hospital to evaluate the incidence and types of malignancies in these patients. The incidence rate of malignancy was 14.4% (52/360). Colorectal cancer was the most commonly associated malignancy (20.9%), followed by skin cancer (16.4%), gastric cancer (10.4%), and lung cancer (10.4%). The calculated age- and sex-standardized incidence ratio of malignancies was 1.235 (95% CI 0.952-1.601) which indicated that the malignancy rate was higher in patients with psoriasis than in the general population, although the difference was not statistically significant. Furthermore, the multivariate analysis revealed increased risk of malignancy in males (HR = 3.15; 95% CI 1.381-7.187; p < 0.001), psoriasis onset at older age (HR = 1.08; 95% CI 1.058-1.111; p < 0.01), and psoriatic erythroderma (HR = 4.44; 95% CI 1.354-14.581; p < 0.05). We also observed that treatment with biological agents tends to reduce the risk of developing malignancy; however, no statistical significance was found. These results suggest that periodic screening for malignancy should be recommended in patients with psoriasis having these risk factors and in those with poorly controlled psoriatic inflammation.