Hyponatraemia is a predictor of clinical outcome for malignant pleural mesothelioma

Hyponatraemia is one of the most common tumour-related electrolyte disorders. Several clinical, histological and serum factors have been found to influence prognosis, but, to date, there are no studies focusing on the prognostic role of hyponatraemia in mesothelioma. The aim of this study was to assess the prognostic role of hyponatraemia in malignant pleural mesothelioma. We analysed 62 consecutive patients with histologically or cytologically proven advanced malignant pleural mesothelioma undergoing chemotherapy at our institution between January 2003 and September 2013. All patients received a first-line pemetrexed-based chemotherapy. A second-line chemotherapy was administered to 29 patients. The onset of hyponatraemia (serum sodium < 135 mEq/L) during the treatment was significantly related to a worsened median overall survival (7.93 vs 13.48 months; p = 0.0069). The occurrence of hyponatraemia during first-line chemotherapy (cutoff 135 and 130 mEq/L) was significantly associated to a shorter median progression-free survival (p = 0.0214). Results were also similar in the subgroup receiving a second-line treatment. At the multivariate analysis, including haemoglobin and sodium level at the beginning of first-line chemotherapy, age, gender, smoking habit, job exposure and performance status, only hyponatraemia was found to be an independent factor (p = 0.029). Hyponatraemia was also found to be a predictive factor for both first-line chemotherapy, being related to poorer response to pemetrexed-based chemotherapy (p = 0.047) and second-line chemotherapy (p = 0.044). Our results show that hyponatraemia might be considered a negative prognostic parameter in malignant pleural mesothelioma patients. To our knowledge, this is the first study to evaluate the association of hyponatraemia with the outcome of malignant pleural mesothelioma patients.