Authors' reply.

Sir,

We thank the authors[1] for their interest in our publication on DR-70 immunoassay and malignant pleural effusion.[2] Authors correctly pointed out about the diagnostic property of the test. The DR-70 assay seems to be high in presence of underlying cancer (such as lung, stomach, breast and rectum cancers) but false positive results can also be seen in some benign conditions (such as tuberculosis and rheumatoid arthritis). It could not point towards the type of underlying cancer but sensitivity of the assay was maximum i.e. 92% in case of breast cancers at 95% specificity level in a previous study.[3] A battery of tests should be performed in a patient of suspected cancer with high DR-70 value to diagnose the underlying cancer early and correctly. We do not agree with the authors’ statement that presence of high level of the assay means no usefulness of the test in early detection of lung cancer. A recent study had mentioned the role of DR-70 in early diagnosis of lung cancer at a cutoff value of 1.0 μg/ml with a sensitivity of 87% and specificity of 95%.[4] DR-70 is a useful assay but further larger studies are required at different stages of cancer to identify its role as a screening biomarker for cancer or as a prognostic marker for cancer. The main problem relies on the fact that the test is still costly according to Indian perspective (3,200 INR) and cost effectiveness of the test needs to be addressed.