Prognostic significance of minimal pleural effusion in non-small cell lung cancer patients.

Abstract

e19152 Background: Malignant pleural effusion (MPE) was defined by the presence of malignant cells in pleural space. Accurate characterization of pleural effusion (PE) is an essential part in staging the disease for adequate management. At diagnostic evaluation, minimal pleural effusion (mPE) that is too small amount PE to examine the presence of malignant cells through thoracentesis is present outside scope of current staging system. Therefore whether mPE has prognostic impact or not is an important clinical issue needed to be investigated. Methods: 1,382 consecutive stage IIIB, IV NSCLC patients were retrospectively enrolled from Inha Lung Cancer Cohort. Information regarding smoking habits, ECOG PS, Charlson comorbidity index score, weight loss in 6 months before diagnosis, levels of hemoglobin, albumin, alkaline phosphatase and calcium at the time of diagnosis, treatment, followed-up and survival status was analyzed as potential confounding factors. All patients were performed staging work-up and followed-up at Inha university hospital. The mPE was defined as less than 1 cm of maximal thickness on contrast enhanced chest CT scan at diagnosis and its presence was not considered in staging the disease. Results: According to status of PE at diagnosis, patients were classified into no PE, mPE and MPE. No PE was presented in 614 patients (44.4%); mPE in 339 patients (24.5%); malignant PE in 356 patients (25.8%). PEs of 73 (5.3%) patients was not evaluated. Overall survival of patients with mPE or MPE was shown to be significantly shorter than those of patients with no PE (MST, 9.67 for no PE, v 6.60 for mPE v 5.37 months for MPE, log-rank p<.0001), even after adjustment for age, smoking habits, ECOG PS, Charlson comorbidity index score, weight loss, hemoglobin, albumin, alkaline phosphatase, calcium, histology, T subset, N subset, M subset, and treatment status (hazard ratios, 95% CIs and Cox p: 1.18, 1.023 to 1.373 and .024 for mPE; 1.545, 1.314 to 1.816 and <.0001 for MPE). Conclusions: The mPE is commonly encountered clinical situation in advanced stage NSCLC patients. These results suggest that presence of mPE at diagnosis confers grave prognosis like MPE, in spite of its nature.