Outdoor ambient air pollution and post-operative outcomes in gastric cancer: a multi-center cohort study

Background: Ambient air pollution is an emerging risk factor for cancer development, but its impact on post-operative recovery and survival in gastric cancer remains unclear. This study aimed to assess the association between long-term preoperative exposure to fine particulate matter (PM 2.5 ), nitrogen dioxide (NO 2 ), and ozone (O 3 ) and post-operative complications and survival in patients undergoing curative gastric cancer surgery. Materials and methods: This multi-center cohort study included 2194 patients from three major gastric cancer centers in Southwest China between 2011 and 2024. Individual exposure to PM 2.5 , NO 2 , and O 3 was estimated using high-resolution geographic models. Multivariate logistic and Cox regression models were used to assess the association between air pollutants and post-operative complications and overall survival, adjusting for clinical, environmental, and socioeconomic variables. Results: Higher PM 2.5 exposure was significantly associated with increased risk of overall complications (OR = 1.014, 95% CI 1.007–1.020, P < 0.001) and reduced overall survival (HR = 1.008, 95% CI 1.003–1.013, P = 0.002). PM 2.5 primarily affected respiratory complications (OR = 1.012, 95% CI 1.003–1.021, P = 0.008) and nutrition and metabolism complications (OR = 1.020, 95% CI 1.010–1.030, P < 0.001). O 3 exposure was inversely associated with complication risk (OR = 0.971, 95% CI 0.957–0.986, P < 0.001), while NO 2 showed no significant association with either outcome. The associations remained robust in multi-pollutant and sensitivity analyses. Conclusions: PM 2.5 is an independent risk factor for post-operative complications and poor survival in gastric cancer patients. O 3 may confer a protective effect. Environmental exposures should be integrated into perioperative risk assessments and public health strategies, particularly in regions with high air pollution levels.