Several studies have demonstrated that serum WFDC2 levels are valuable for the diagnosis or prognosis of lung cancer (Nagy et al., 2014; Korkmaz et al., 2018; Liu et al., 2013; Zhong et al., 2017; Lamy et al., 2015; Iwahori et al., 2012; Lan et al., 2016). Here, WFDC2 is linked to lung cancer.