Changes in pulmonary function tests predict radiological response to chemotherapy in malignant pleural mesothelioma

Response to chemotherapy in malignant pleural mesothelioma (MPM) is usually evaluated by radiological criteria, but no common agreement exists on their validity, yet. The cytoreductive effect of chemotherapy on pleural thickening may make the lung more expansible, reducing the restrictive ventilatory impairment. The aim of this study was to evaluate the changes in pulmonary function following chemotherapy in patients with MPM and to correlate these findings with radiological changes.

Between 2004 and 2011, 62 consecutive patients (74% males, median age 63 years) were prospectively investigated. Modified RECIST criteria were used for radiological evaluation of response to chemotherapy. All patients underwent pulmonary function tests before and after three cycles of platinum-based chemotherapy. Changes between baseline and post-chemotherapy pulmonary function values (Δ) and their differences were assessed by means of Student's paired and unpaired t-test, respectively. Receiver operating characteristic (ROC) curve analysis was performed on spirometric parameters significantly associated with response.

Thirty (48.4%) patients had a radiological stable disease (S), 23 (37.1%) a partial response (R) and 9 (14.5%) a progressive disease (P). ΔFEV1%pred (R: 18.1 ± 18.5%; S: 0.5 ± 9.3%; P: -11 ± 13.5%; P < 0.0001), ΔFVC%pred (R: 16.1 ± 11.8%; S: 0.4 ± 11.2%; P: -9.2 ± 14.6%; P < 0.0001) and ΔVC%pred (R: 12.9 ± 15.7%; S: 1.5 ± 12.1%; P: -6.1 ± 13.2%; P = 0.001) were significantly associated with radiological response. A significant correlation was observed between ΔFEV1%pred (r = 0.46, P = 0.01), ΔFVC%pred (r = 0.43, P = 0.02) and % change in linear tumour measurement. ROC curve analysis using dichotomized radiological response (P/S vs R) as classification variables showed AUC = 0.88 (95%CI: 0.77-0.95) for ΔFEV1%pred (optimal cut-off value: +7%, sensitivity: 83%, specificity: 82%, PPV: 73%, NPV: 89%) and AUC = 0.86 (95%CI: 0.75-0.94) for ΔFVC%pred (optimal cut-off value: +6%, sensitivity: 82%, specificity: 74%, PPV: 64%, NPV: 88%).

Dynamic lung volumes and radiological changes after chemotherapy seem directly related. Lung function changes could be an additional tool to better evaluate the response to chemotherapy in MPM.