Role of DR-70 immunoassay in suspected malignant pleural effusion

A good proportion of patients with undiagnosed pleural effusion (PE) turn into malignancy over a period of time. Identification of positive biomarker may help in selecting the individuals who require close follow-up.

The aims of this study were to evaluate the role of DR-70 immunoassay in suspected malignant PE.

We conducted a cross-sectional study among 89 patients of suspected malignant PE and 50 normal subjects (NS) were taken as control.

Patients with exudative PE; who had pleural fluid lymphocyte count greater than 50% and adenosine deaminase less than 30 U/L were taken as cases. We had selected NSs among relatives of patients having normal blood chemistry and radiological investigations. Sensitivity and specificity of the test to differentiate malignant and non-malignant PE and also to identify PE with underlying malignancy was analyzed.

Mean value of DR-70 in NS was found to be 0.83 ± 0.273 mg/L without any significant difference between males (0.82 mg/L) and females (0.85 mg/L). Mean value of DR-70 in PE with underlying cancer was 5.03 ± 3.79 mg/L. Sensitivity (80%) and specificity (77.78%) of the test was maximum in PE with underlying cancer using cut-off value of 2 mg/L. Mean value DR-70 in malignant PE was 5.18 ± 3.75 mg/L and in non-malignant PE was 3.73 ± 3.74 mg/L without any statistically significant difference (P = 0.08).

DR-70 assay has high sensitivity in detecting underlying lung cancer, but has no role in differentiating malignant PE from non-malignant PE.