Evaluation of the prognostic significance of human mammaglobin expression in pleural effusion from patients with negative thoracoscopy.

Abstract

10534 Background: It has been reported that application of the RT-PCR test for human mammaglobin (hMAM) may provide diagnostic information to evaluate the neoplastic origin of pleural effusion (PE). Our main goal was to assess the value of hMAM RT-PCR as an adjunctive test to thoracoscopic biopsy which represents the conventional gold standard in PE diagnosis. Methods: This study included 288 patients who underwent thoracoscopy. Histological analysis of pleural biopsies showed malignant diseases (MT) in 155/288 (53.8%) patients and non-malignant diseases (NMT) in 133/288 (46.2%) patients. The cells obtained from PE were analyzed by a nested RT-PCR protocol for hMAM mRNA gene detection. We evaluated the association between hMAM expression and MT vs NMT status by the diagnostic odds ratio (DOR). The diagnostic performance parameters of sensitivity (Se), specificity (Sp), accuracy (Ac), predictive positive value (PPV), predictive negative value (PNV) were also analysed. In addition, the relative risk of cancer in negative thoracoscopy patients showing hMAM expression in PE was evaluated by multivariate logistic regression analysis. Results: hMAM transcript was found in 68/288 (23.6%) of the total PE. Among them, 51/155 (Se=32.9%) positive cases were from MT and 17/133 (1-Sp=12.8) were from NMT. Statistical analysis showed significant correlation between hMAM expression and MT (DOR value of 3.04). The diagnostic performance parameters of hMAM detection were as follows: Sp=87.2.%, Ac=58.0%, PPV=75.0% and NPV=52.7%. The 18 month follow up of negative thoracoscopy patients showed that 5/17 (29,4%) of hMAM positive PE had a tumour in contrast to 10/126 (7.9%) of hMAM negative PE with a relative risk of 4.6 for developing malignancy (p=0.023). Conclusions: Our findings suggest a prognostic value of PE hMAM in non-specific pleuritis and may point out a false-negative thoracoscopy.