Connecting gastrointestinal cancer risk to cadmium and lead exposure in the Chaoshan population of Southeast China

Cadmium (Cd) and lead (Pb) pose a serious threat to human health because of its carcinogenicity. China ranks first according to the Global Cancer Report for 2014 in newly diagnosed gastrointestinal cancers and cancer deaths. The aim of the present study was to evaluate the association of Cd and Pb burden with the risk of gastrointestinal cancers in a hospital-based case-control study from southern regions of China, Chaoshan area. A total of 279 hospitalized patients were recruited in this study, of which 167 were gastrointestinal cancer cases (70 esophageal cancer, 51 gastric cancer, and 46 colorectal cancer), and 112 controls were recruited from two hospitals in the Chaoshan area of southeast China. Basic clinical data and information on gender, age, and other demographic characteristics were collected from medical records. Blood Cd and Pb levels were detected by graphite furnace atomizer absorption spectrophotometry (GFAAS). Blood Cd/Pb levels and over-limit ratios between cases and controls were compared by Mann-Whitney U and Kruskal-Wallis H tests. We used logistic regression to estimate odds ratios (ORs) as measures of relative risk and explored the relationships between blood Cd/Pb levels and gastrointestinal cancer risk and clinicopathological characteristics. Median levels of blood Cd and Pb in cases (2.12 and 60.03 μg/L, respectively) were significantly higher than those of controls (1.47 and 53.84 μg/L, respectively). The over-limit ratios for Cd (≥ 5 μg/L) and Pb (≥ 100 μg/L) in the cases were both higher than that of controls. Blood Cd levels had a tendency to accumulate in the human body with gender, age, and tobacco smoking, while blood Pb levels only were associated with tobacco smoking. The logistic regression model illustrated that gastrointestinal cancers were significantly associated with blood Cd levels and blood Pb levels. The concentrations of Cd and Pb in patients with T3 + T4 stage were markedly higher than in patients with T1 + T2. On the other hand, blood Cd levels were dramatically increased in the distant –metastasis (M1). Blood Cd and Pb levels are significantly higher in gastrointestinal cancers compared to controls. Cd and Pb appear to be risk factors for gastrointestinal cancers in Chaoshan region, and higher levels of Cd and Pb may promote the occurrence and progression of gastrointestinal cancers.