Risk of Psoriasis in Postgastrectomy Gastric Cancer Survivors: A Nationwide Population-Based Cohort Study

BACKGROUND: Although patients with psoriasis have an increased risk of cancers, little is known about the risk of psoriasis in cancer patients. OBJECTIVE: We aimed to comparatively analyze the incidence and risk factors of psoriasis in gastric cancer patients who underwent gastrectomy and in the general population. METHODS: A nationwide retrospective cohort of 52,608 gastric cancer survivors (2007~2015) was compared to 123,438 matched controls from the general population to estimate the incidence and hazard ratio (HR) of new-onset psoriasis. We also calculated the HRs for psoriasis according to adjuvant cancer treatment, obesity, and vitamin B(12) supplementation in gastric cancer survivors. RESULTS: During a mean follow-up of 6.85 years, 645 of the 52,608 gastric cancer patients developed psoriasis, while 1,806 in the 123,438 matched control group developed psoriasis. Gastric cancer patients had a decreased risk of psoriasis (HR, 0.86; 95% confidence interval, 0.79~0.94), especially those who underwent subtotal gastrectomy. We found that vitamin B(12) supplementation for more than 3 years had an additive effect on decreasing the risk of psoriasis in gastric cancer patients who underwent subtotal gastrectomy. Total gastrectomy, radio/chemotherapy, and obesity did not affect the risk of psoriasis in gastric cancer survivors. CONCLUSION: The incidence of psoriasis is slightly lower in gastric cancer survivors than in the general population. Our results suggest that the development of psoriasis may be reduced by removing the source of systemic inflammation caused by Helicobacter pylori infection through subtotal gastrectomy in gastric cancer survivors.