Background: The aim of our study is to determine the clinical availability accessibility of cancer ratio and cancer ratio plus formulations, previously validated and reported to have clinical value in distinguishing malignant pleural effusion from tuberculosis pleurisy and parapneumonic effusion.
Materials and Methods: Retrospective study of patients hospitalized with Malignant Pleural Effusion (MPE), tuberculosis (TPE) and pararapneumonic effusion (PPE) between 2009 and 2018.
Results: Totally 232 patients, 101(43.5 %) having MPE, 86 (37.1 %) having PPE and 45 (19.4 %) TPE were examined. When compared with each other, ‘’serum LDH / PS Lymphocyte %’’, ‘’Cancer ratıo’’ and ‘’Cancer ratıo plus’’ values were statistically different between the groups (p = 0.021, p <0.001 and p = 0.015, respectively). In multivariate logistic regression analysis, cancer ratio, serum LDH: pleural fluid lymphocyte count ratio was in positive correlation with MPE. The sensitivity and specificity of ‘’cancer ratio’’, “cancer ratio plus” and ‘’ratio of serum LDH: pleural fluid lymphocyte count’’ were 84.2 % (95% CI 75.6– 90.7) and 52.7 (95% CI 43.8– 61.5), and 82.2 % (95% CI 73.3– 89.1) and 45.8 (95%CI 37.1– 54.7), 53.5% (95% CI 43.3– 63.5) and 67.2% (95% CI 0.68–0.94) at the cut-off level of >14.25, >28.7, and >636, respectively. When considering only MPE and TPE patients, the specificity of cancer ratıo and cancer ratıo plus increased.
Conclusion: The cancer ratio plus rate ( the ratio of ‘’cancer ratio’’formulation  to the percentage of differential pleural lymphocyte count ) was almost the same as the cancer ratio in separating the malignant pleural effusion from the TPE and PPE, while it has better specificity only in differentiating malignant effusions from tuberculosis effusions.