Sir,The topic of DR-70 immunoassay and malignant pleural effusion (PE) is an interesting article in chest oncology.[1] In a study, Sengupta et al. reported that “DR-70 assay has high sensitivity in detecting underlying lung cancer, but has no role in differentiating malignant PE from non-malignant PE.”[1] There are many considerations on actual clinical use of DR-70 immunoassay. First, the diagnostic property of this assay is only fair[12] and there are several cancers (such as lung, stomach, breast and rectum cancers) that can induce abnormal results.[2] In addition, the significant high level can be seen in the cases with advanced disease, which means no usefulness for early detection.[3] Finally, there is still no report confirming the cost-effectiveness of this new test.