A meta-analysis on association between welding fumes and lung cancer based on case-control studies

Background Welding fumes are a risk factor of prescript occupational diseases in China. In 2017, the International Cancer Research Institute listed welding fumes as a human carcinogen (Group 1); therefore, the hazards of welding fumes to workers' health cannot be ignored.

Objective This study aims to evaluate the association between welding fumes and lung cancer.

Methods We searched Chinese literatures from CNKI and Wanfang databases and English literatures from PubMed, Embase, and Web of Science, using keywords in either Chinese or English such as "welding fumes", "welding", "welder", "lung cancer", "neoplasms", "tumor", "case-control study", and "occupational cancer". The obtained literatures were subject to strict inclusion and exclusion criteria. Either fixed-effect model or random-effect model was selected according to the results of heterogeneity test to combine the included effect values. Egger test was used to test publication bias.

Results A total of 14 case-control studies on occupational exposure to welding fumes and lung cancer were included. Because I²=76.4%, the random-effect model was used to combine effect values, and the results showed that the combined OR was 1.46 (95%CI:1.21-1.77), indicating that the exposure to welding fumes increased the risk of lung cancer. The results of Egger test showed that t=0.62 and P>0.05, indicating that the funnel chart was basically symmetrical, suggesting no publication bias. The results of subgroup analysis was I² >50%, and did not prove homogeneity across the included studies. The results of sensitivity analysis did not change significantly, indicating robust meta-analysis results.

Conclusion Exposure to welding fumes may increase the risk of lung cancer.