Abstract
BACKGROUND: Gastric cancer is a formidable global heath challenge, especially in China. We aimed to investigate temporal trends and spatial variations of gastric cancer incidence and mortality in Gansu Province, which has the highest incidence rate of gastric cancer in China, and sought to explore the role of various geographic and environmental factors played in the variations of incidence rates of gastric cancer. METHODS: We sourced the incidence and mortality data for gastric cancer from the China Cancer Registry Annual Report and environmental data from National Soil Series Survey and Compilation of Soil Series of China and China National Environmental Monitoring Centre. We used joinpoint regression models to examine the temporal trends in age-standardised incidence rate (ASIR) and age-standardised mortality rate (ASMR) for gastric cancer between 2010 and 2018. We used the Pearson correlation coefficient, robust linear regression, and least-squares regression models to explore the associations between environmental parameters and gastric cancer incidence. RESULTS: The ASIR of gastric cancer per 100 000 population in Gansu Province showed a slightly increasing trend from 2010 (77.75; 95% confidence interval (CI) = 73.98, 81.52) to 2014 (85.20; 95% CI = 80.36, 90.04) and then started to decrease to 51.77 (95% CI = 49.14, 54.40) in 2018. The mortality rate of gastric cancer per 100 000 population remained stable from 2010 (55.69; 95% CI = 52.38, 59.01) to 2017 (51.06; 95% CI = 48.11, 54.01), while the rate showed a noticeable decline in 2018 (33.37; 95% CI = 31.26, 35.48). In 2018, significant variations in the ASIR (more than 5-fold) and ASMR (more than 11-fold) were observed across 15 registries in Gansu Province. Associations between soil properties at different depths and ASIR were calculated for 15 registries in Gansu Province, and statistically significant indicators included soil pH, total nitrogen density (TND), total phosphorus (TP), and soil organic carbon density (SOCD) (P < 0.05). No statistically significant correlation was found between ASIR and ambient air pollutants and surface water properties. The environmental variables explained about 37.9% of the variability in regional level ASIR of gastric cancer (adjusted R(2) = 0.379, F = 3.136, P = 0.046). In addition, strong correlations among soil pH, TND, TP, and SOCD. While chemical fertilisers have been documented to induce soil acidification and elevate N, P, and C levels, we thus compared the annual trends in the application of chemical fertilisers with the ASIR of gastric cancer in Gansu Province, revealing consistent patterns. The correlation coefficient between annual quantity of applied chemical fertilisers and ASIR was 0.638. CONCLUSIONS: We observed significant geospatial variations in the ASIR and ASMR of gastric cancer in Gansu Province, which has the highest incidence rate of gastric cancer in China, as well as a novel correlation between the usage of chemical fertilisers and the incidence of gastric cancer, highlighting the need for further research in this area.