Prognostic Value of Pleural Fluid pH in Malignant Epithelial Mesothelioma after Talc Poudrage

Abstract

Background: Current staging schemes for malignant mesothelioma are inadequate. The most accurate staging may require pneumonectomy – a procedure associated with many complications. The pH of pleural fluid (ppH) predicts survival in nonmesotheliomatous malignant pleural effusions, suggesting that this noninvasive test might be useful for prognostication in malignant mesothelioma. Objective: It was the aim of this study to determine whether baseline ppH correlates with survival in malignant epithelial pleural mesothelioma. Methods: We reviewed survival data in patients treated with thoracoscopic talc pleurodesis whose final diagnosis was epithelial malignant pleural mesothelioma and whose chart recorded a ppH determination performed just before thoracoscopy. We monitored 26 patients until April 2002 (25 of these patients died), identifying cutoff ppH values that discriminate best for survival; Cox proportional hazards models were recursively run by increasing the ppH cutoff value by 0.02 each time. Results: The mean follow-up time was 19 ± 14 months. Mean ppH was 7.30 ± 0.09, and median ppH was 7.32. Several cutoff points correlated with a statistically significant difference in survival, but ppH 7.32 was associated with the greatest value for the area under the curve. Patients with ppH >7.32 lived a median of 21.2 months (95% confidence interval 16.5–30.0 months) after diagnosis compared with patients who had ppH ≤7.32 and lived a median of 13.4 months (95% confidence interval 4.5–16.2 months; p = 0.0194). Conclusions: Baseline ppH correlates with survival in epithelial mesothelioma patients treated palliatively with pleurodesis by thoracoscopic talc poudrage. This noninvasive test – ppH – should be included when staging patients with malignant mesothelioma.

Practical utility of insulin‐like growth factor II mRNA‐binding protein 3, glucose transporter 1, and epithelial membrane antigen for distinguishing malignant mesotheliomas from benign mesothelial proliferations

“…The sensitivity and specificity of EMA has been reported in 68 to 100% and 40 to 100% for malignant mesothelioma. 12,15,18,19,23 Hasteh et al 15 reported that EMA was positive in all 52 mesotheliomas and 9% of 64 benign cases. But, Kuperman et al 18 showed that EMA was expressed in 77% of 43 mesotheliomas and 31% of 35 benign effusions.…”

“…The sensitivity and specificity of EMA has been reported in 68 to 100% and 40 to 100% for malignant mesothelioma . Hasteh et al .…”

Chemical pleurodesis – a review of mechanisms involved in pleural space obliteration

“…On the other hand, it must be admitted that pleural fluid pH in MPE is associated with the risk of lung entrapment and increased mortality. Also, it was suggested, that it is not only associated with impaired lung re-expansion, but also with inhibition of the biological processes leading to pleurodesis [71]. The role of the PMC count may be confirmed by the observation that pleurodesis in spontaneous pneumothorax which is characterized by a large number of intact mesothelial cells requires smaller doses of the sclerosing agents [50].…”

Mechanisms of Pleurodesis

“…In our thoracoscopy series, we found a complete successful talc pleurodesis in 79% of the patients with pH ≥7.30, whereas it was successful in only 40% of those with pH <7.20, and in none of the patients with pH <7.15 [17]. A low pleural pH has been associated with trapped lung and poor survival, and there are some clues suggesting that a low pH does not only mean that there is a thick visceral pleura with difficult lung reexpansion [24], but that it would also inhibit some of the biological processes leading to a good pleurodesis by itself.…”