Prognostic factors of recurrence of malignant pleural effusion: what is the role of neoplasia progression?

Background: It is known that malignant pleural effusion (MPE) recurs rapidly, in a considerable number of patients. However, some patients do not have MPE recurrence. Since MPE is associated with an average survival of 4-7 months, accurate prediction of prognosis may help recognize patients at higher risk of pleural recurrence, aiming to individualize more intensive treatment strategies.

Methods: A prospectively assembled database of cases with pleural effusion treated at a single institution analyzed a subset of patients with symptomatic MPE. Prognostic factors for pleural recurrence were identified by univariable analysis using Kaplan-Meier method and the log-rank test was used for the comparison between the curves. Univariate and multiple Cox regression models were used to evaluate the risk (HR) of recurrence. Receiver operating characteristics (ROC) analysis determined the cutoff points for continuous variables.

Results: A total of 288 patients were included in the analysis. Recurrence-free survival was of 76.6% at 6 months and 73.3% at 12 months. Univariable analysis regarding factors affecting postoperative recurrence was: lymphocytes, platelets, pleural procedure, chemotherapy lines and number of metastases. The independent factors for recurrence-free survival were pleural procedure and chemotherapy lines. Patients who were submitted to pleurodesis had a protective factor for recurrence, with an HR =0.34 (95% CI, 0.15-0.74, P=0.007). On the other hand, patients submitted to the 1st and 2nd line of palliative CT had, respectively, an HR risk = 2.81 (95% CI, 1.10-7.28, P=0.034) and HR =3.23 (95% CI, 1.33-7.84, P=0.010).

Conclusions: patients receiving the first or second line of systemic treatment have a higher risk of MPE recurrence when compared to patients who underwent MPE treatment before starting the systemic treatment. The definitive treatment of MPE, such as pleurodesis, was associated with a lower risk of MPE recurrence.