title: Prognostic impact of minimal pleural effusion in non-small-cell lung cancer.
abstract: OBJECTIVE
  Minimal (< 10 mm thick) pleural effusion (PE) may represent an early phase of malignant PE, but its clinical relevance has rarely been studied. Therefore, we examined the proportion of minimal PE in patients with non-small-cell lung cancer (NSCLC) and its impact on survival. We also considered possible accumulation mechanisms in our data set.
  
  
  METHODS
  On the basis of PE status from chest computed tomography scans at diagnosis, 2,061 patients were classified into three groups: no PE, minimal PE, and malignant PE. Twenty-one variables associated with four factors-patient, stage migration, tumor, and treatment-were investigated for correlation with survival.
  
  
  RESULTS
  Minimal PE presented in 272 patients (13.2%). Of 2,061 patients, the proportion of each stage was the following: 5.2% stage I, 10.9% stage II, 13.2% stage IIIA, 23.8% stage IIIB, and 13.9% stage IV. Minimal PE correlated significantly with shorter survival time than did no PE (median survival time, 7.7 v 17.7 months; log-rank P < .001), even after full adjustment with all variables (adjusted hazard ratio, 1.40; 95% CI, 1.21 to 1.62). Prognostic impact of minimal PE was higher in early versus advanced stages (Pinteraction = .001). In 237 patients (87.8%) with minimal PE, pleural invasion or attachment as a direct mechanism was observed, and it was an independent factor predicting worse survival (P = .03).
  
  
  CONCLUSIONS
  Minimal PE is a commonly encountered clinical concern in staging NSCLCs. Its presence is an important prognostic factor of worse survival, especially in early-stage disease.
authors.affiliation: Jeong-Seon Ryu, Azra Memon, Seul-Ki Lee, Hae-Seong Nam, Hyun-Jung Kim, and Jae-Hwa Cho, Center for Lung Cancer, Inha University Hospital; Si-Nae Lee, Kyung-Hee Lee, and Seung-Sik Hwang, Inha University Hospital, Incheon, S. Korea; and Hyo Jin Ryu, University of California, Los Angeles, CA.
authors.forename: Jeong-Seon
authors.initials: JS
authors.lastname: Ryu
authors.forename: Hyo Jin
authors.initials: HJ
authors.lastname: Ryu
authors.forename: Si-Nae
authors.initials: SN
authors.lastname: Lee
authors.forename: Azra
authors.initials: A
authors.lastname: Memon
authors.forename: Seul-Ki
authors.initials: SK
authors.lastname: Lee
authors.forename: Hae-Seong
authors.initials: HS
authors.lastname: Nam
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Kyung-Hee
authors.initials: KH
authors.lastname: Lee
authors.forename: Jae-Hwa
authors.initials: JH
authors.lastname: Cho
authors.forename: Seung-Sik
authors.initials: SS
authors.lastname: Hwang
mesh_terms: D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000150:complications* / Q000000981:diagnostic imaging / Q000401:mortality; D015986:Confounding Factors, Epidemiologic; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000150:complications* / Q000000981:diagnostic imaging / Q000401:mortality; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000209:etiology; D016066:Pleural Effusion, Malignant / Q000000981:diagnostic imaging / Q000209:etiology* / Q000401:mortality; D011237:Predictive Value of Tests; D011379:Prognosis; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed