Differentiating Malignant from Tubercular Pleural Effusion by Cancer Ratio Plus (Cancer Ratio: Pleural Lymphocyte Count)

Abstract

Background. We performed prospective validation of the cancer ratio (serum LDH : pleural ADA ratio), previously reported as predictive of malignant effusion retrospectively, and assessed the effect of combining it with “pleural lymphocyte count” in diagnosing malignant pleural effusion (MPE). Methods. Prospective cohort study of patients hospitalized with lymphocyte predominant exudative pleural effusion in 2015. Results. 118 patients, 84 (71.2%) having MPE and 34 (28.8%) having tuberculous pleural effusion (TPE), were analysed. In multivariate logistic regression analysis, cancer ratio, serum LDH : pleural fluid lymphocyte count ratio, and “cancer ratio plus” (ratio of cancer ratio and pleural fluid lymphocyte count) correlated positively with MPE. The sensitivity and specificity of cancer ratio, ratio of serum LDH : pleural fluid lymphocyte count, and “cancer ratio plus” were 0.95 (95% CI 0.87–0.98) and 0.85 (95% CI 0.68–0.94), 0.63 (95% CI 0.51–0.73) and 0.85 (95% CI 0.68–0.94), and 97.6 (95% CI 0.90–0.99) and 94.1 (95% CI 0.78–0.98) at the cut-off level of >20, >800, and >30, respectively. Conclusion. Without incurring any additional cost, or requiring additional test, effort, or time, cancer ratio maintained and “cancer ratio plus” improved the specificity of cancer ratio in identifying MPE in the prospective cohort.

The clinical utility of joined detection of cancer ratio, cancer ratio plus, Interferon gamma (IFN-ϒ) & Carcinoembryonic antigen (CEA) in differentiating lymphocytic pleural effusions

“…AUC was 0.947. These were in accordance with Verma et al [7] who reported the ROC-derived cutoff level of > 20 for cancer ratio yielded sensitivity, specificity, positive likelihood ratio (PLR), and negative likelihood ratio (NLR) of 0.95, 0.85, 16, 0.13 respectively [7].…”

“…The accuracy of cancer ratio was enhanced when combined with pleural lymphocyte count (cancer ratio: pleural fluid lymphocyte count), what is called cancer ratio plus; its cutoff level in differentiating MPE from other lymphocytic effusions (≥ 41) raised the sensitivity and specificity to 93.6% and 91.7% respectively that was in high agreement with Verma et al [7] who reported that the cutoff level of "cancer ratio plus" of > 30 had PLR of 41 suggesting that patients with cancer have about 41-fold higher probability of having "cancer ratio plus" of > 30 in comparison with patients without cancer. In contrast, NLR at this cutoff was found to be 0.06 suggesting that if the "cancer ratio plus" is < 30, the chance that the diagnosis is cancer is 6%, which is low enough to make the patient unlikely to be diagnosed as having cancer.…”

“…Among the routinely performed biochemical tests for investigating exudative pleural effusion; there are serum lactate dehydrogenase (LDH), pleural adenosine deaminase (ADA), and pleural lymphocyte count. This reciprocal change presents an opportunity to combine these results developing a ratio with the diagnostic power to differentiate MPE from TPE in a cost-effective, timely, and universally applicable manner [7].…”

Predictors of Malignancy in Lymphocytic Pleural Effusions

“…Combining the cancer ratio with the lymphocyte count of the pleural fluid, the cancer ratio plus at a value of > 30 improved the sensitivity and specificity of distinguishing malignant from tuberculous pleural effusions to 97% and 94% respectively. 8 Our study had a positive yield in pleural fluid cytology in 59.5% cases. The commonest histology identified was adenocarcinoma of the lung (44.7%).…”

“…7,8 At a cut-off level of > 20, the cancer ratio showed a sensitivity of 95% and a specificity of 85% in diagnosing malignancy in this study. 8 Research is currently planned in our hospital to find out the best cut-off value of cancer ratio (serum LDH/pleural fluid ADA), which can identify malignancy as the cause of lymphocytic pleural effusion. Since both the investigations under study are done routinely as part of the initial evaluation of effusions, the result of the study will be of great help in planning further confirmative tests for diagnosing malignancy in suspected cases.…”