Minimal Pleural Effusion Predicts Poorer Survival in Non–Small Cell Lung Cancer
In a study reported in the Journal of Clinical Oncology, Ryu et al found that presence of minimal pleural effusion is associated with worsened survival in patients with non–small cell lung cancer (NSCLC) compared with no effusion, particularly among patients with early-stage disease.
Study Details
The study involved 2,340 consecutive patients with histologic diagnosis of stage I to IV NSCLC at Inha University Hospital from 2002 to 2010; after exclusion of patients who underwent noncontrast chest computed tomography scans and those who did not undergo brain imaging or whole-body bone scans, 2,061 patients remained in the analysis. Patients were classified as having no pleural effusion, minimal effusion defined as < 10 mm in thickness, or malignant effusion, and interaction of these classifications with patient, stage migration, tumor, and treatment factors were investigated for correlation with survival.
Among all patents, 1,397 (67.8%) had no pleural effusion, 272 (13.2%) had minimal effusion, and 392 (19.0%) had malignant effusion. Disease stages were I in 5.2% of patients, II in 10.9%, IIIA in 13.2%, IIIB in 23.8%, and IV in 13.9%.
Predicts Poorer Survival
Compared with no pleural effusion, minimal effusion was associated with significantly reduced median overall survival (7.7 vs 17.7 months, P < .001), with a hazard ratio [HR] of 2.33 (P < .001 for trend) on unadjusted analysis. Minimal effusion was a consistent and significant factor in predicting worse overall survival at every step of Cox proportional hazards modeling when adjusted in a stepwise fashion for each group of variables related to patient, stage migration, tumor, and treatment.
On the final model adjusting for sex, age, smoking habit, Charlson comorbidity score, Eastern Cooperative Oncology Group performance status, weight loss, hemoglobin, albumin, alkaline phosphatase, calcium, histology, EGFR mutation, tumor size, N stage, number of organs affected by metastasis, positron-emission tomography, and treatment, minimal effusion was still significantly associated with greater risk of death vs no effusion (HR = 1.40, 95% confidence interval [CI] = 1.21–1.62, P < .001 for trend). Malignant pleural effusion vs no effusion was associated with increased risk of death on unadjusted analysis (HR = 2.80, P < .001 for trend) and on the multivariate analysis (HR = 1.86, P < .001 for trend).
Survival by Stage
The prognostic impact of minimal pleural effusion was greater in early vs advanced disease stages (P < .001 for interaction). On multivariate analysis, hazard ratios for risk of death for minimal effusion vs no effusion by stage were 2.07 (95% CI = 1.06–4.05) in stage I disease, 2.24 (95% CI = 1.02–4.94) in stage II, 1.62 (95% CI = 0.95–2.94) in stage IIIA, 1.57 (95% CI = 1.08–2.28) in stage IIIB, and 1.16 (95% CI = 0.98–1.39) in stage IV.
Among the 270 patients with minimal pleural effusion for which a cause of accumulation was identified, 237 (87.8%) had a direct mechanism of invasion or attachment to pleura by tumor, and presence of such a direct mechanism was an independent predictor of worse overall survival (P = .03).
The investigators concluded, “Minimal [pleural effusion] is a commonly encountered clinical concern in staging NSCLCs. Its presence is an important prognostic factor of worse survival, especially in early-stage disease.”
Jeong-Seon Ryu, MD, PhD, of Inha University Hospital, Incheon, South Korea, is the corresponding author for the Journal of Clinical Oncology article.
The study was supported by the Korea Healthcare Technology R&D Project. The study authors reported no potential conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
