Risk of gastric cancer in chronic obstructive pulmonary disease

Objective Owing to the potential role of the gut-lung axis in carcinogenesis, we assessed the incidence of gastric cancer in patients with chronic obstructive pulmonary disease (COPD). Methods Using Quebec's administrative databases, we assembled a cohort of 118 913 patients aged 40 years and older with COPD from 1995 to 2015. We calculated age-standardized incidence rate ratio (IRR) and 95% confidence interval (CI) for gastric cancer, comparing patients with COPD to the Quebec general population. We evaluated temporal changes in incidence by calculating annual percentage change (APC) and stratified the analysis by anatomical site. Results Between 1995 and 2015, 279 patients with COPD developed gastric cancer (54.0 cases per 100 000 person-years). The overall age-standardized incidence rate in patients with COPD was comparable to the general population (IRR, 1.05; 95% CI, 0.79-1.39). However, the IRR increased over time (APC, 4.40%; P = 0.0101), due to the growing rate of gastric cancer in patients with COPD (APC, 1.90%; P = 0.2666) and the declining rate in the Quebec population (APC, -2.40%; P < 0.0001). Conclusions The overall risk of gastric cancer in patients with COPD did not differ from the general population; however, the risk among patients has increased over the years. These findings provide insights as to whether long-term follow-up for gastric cancer risk in COPD is warranted.