Differentiation between malignant and non-malignant pleural effusion using cancer ratio and other new parameters

Abstract

Introduction In contrast to tuberculous pleurisy (TP), no accurate and commonly accepted biochemical marker of malignant pleural effusion (MPE) has been established. Objectives We aimed to evaluate the ability of a previously reported cancer ratio (CR) to discriminate between MPEs and non-MPEs; to test whether age may have additional value in differentiating MPEs from non-MPEs; and if so, to combine lactate dehydrogenase (LDH) and age with other TP biomarkers in search of an index useful in the identification of MPEs. Patients and methods A retrospective analysis of data from 140 patients with malignant (n = 74), tuberculous (n = 37), and parapneumonic (n = 29) pleural effusions was performed. The diagnostic performance of a test to discriminate between MPEs and non-MPEs was evaluated using the receiver operating characteristic curve analysis. Results Three ratios showed the largest area under the curve (AUC): serum LDH to pleural fluid soluble Fas ligand, age to pleural fluid adenosine deaminase (ADA), and serum LDH to pleural fluid interleukin 18; moreover, the ratios were characterized by high sensitivity (95%, 93.2%, and 92.9%, respectively) and fair specificity (64.8%, 71.2%, and 58.5%, respectively) for differentiating MPEs from non-MPEs. The AUC for CR was lower and showed a sensitivity of 94.6% and a specificity of 68.2%. Conclusions Our study showed a lower specificity of the CR for discriminating between MPEs and non-MPEs than previously reported. We demonstrated that the combinations of serum LDH with other pleural fluid biomarkers of TP have a similar diagnostic performance. We also found that age might be an important factor differentiating between MPEs and non-MPEs and proposed a new age to pleural fluid ADA ratio which has a discriminative potential similar to that of the CR.

Age : pleural fluid ADA ratio and other indicators for differentiating between tubercular and malignant pleural effusions

“…[18] The results were also significantly different from what were reported by Verma [8] and Piotr. [6] The sensitivity and specificity of Cancer Ratio plus were found to be 81.5% (95%CI 73.8%-87.8%) and 80.0% (95%CI 70.2%-87.7%) respectively at the cut-off level of ≤34.74 in our study (Fig. 1D).…”

“…[7,8] In Piotr’s study, malignant PE contained 51.4% of lung cancer patients. [6] The proportions of patients with lung cancer were 75.6% in our study. Serum lactate dehydrogenase (LDH) is an extensive cellular enzyme that increases in a nonspecific manner in response to tissue damage.…”

“…He thought that the sensitivity and specificity of age to pleural fluid ADA was 93.2% and 71.2% respectively for differentiating MPE from nonMPE. [6] The difference may be due to the ) respectively at cut-off level of >21.5. A meta-analysis also showed that the sensitivity and specificity of ADA in the diagnosis of tuberculosis pleural effusion were 0.93 and 0.90, respectively.…”

“…He thought that the sensitivity and specificity of age to pleural fluid ADA was 93.2% and 71.2% respectively for differentiating MPE from nonMPE. [6] The difference may be due to the sensitivity and specificity in Piotr’s study based on MPE. The sensitivity and specificity of pleural fluid ADA were 83.1% (95%CI 75.5–89.1%) and 93.3% (95%CI 86.1–97.5%) respectively at cut-off level of >21.5.…”

“…The proportions of patients with TPE and PPE were 26% and 21% in Piotr’s study. [6] TPE constituted only 28.8% in the study by Verma. [8] His other study included 40 patients with tubercular effusion, 14 with parapneumonic effusion, and 9 with undiagnosed (24.5%, 8.5%, and 5.5%).…”