Prognostic value of the ratio of ground glass opacity on computed tomography in small lung adenocarcinoma: A meta-analysis

Introduction: Lung cancer is the leading cause of cancer-associated death. In many countries, adenocarcinoma is the most common histologic type in lung cancer. Previously, few factors are identified to be prognostic indicators for the patients with small lung adenocarcinoma. Recently, the ground glass opacity (GGO) area found on high-resolution computed tomography (HRCT) scanning was identified as a prognostic indicator in some studies. But no clear consensus has been defined.

Methods: The PubMed/MEDLINE, EMBASE, Cochrane library and SpringerLink electronic databases were searched for articles related to ground glass opacity on computed tomography in patients with small lung adenocarcinoma. Data was extracted and analyzed independently by two investigators. An estimate of the hazard ratio (HR) for comparing high GGO ratio with low GGO ratio was extracted. The respective HRs was combined into a pooled HR, and 95% confidence interval (CI) was calculated for each study. The publication heterogeneity was assessed graphically using performing Beggs' funnel plot. All the statistical tests used in our meta-analysis were performed with STATA version 11.

Results: Thirteen studies, encompassing 2,027 patients, were included in our meta-analysis. Ten of these studies revealed that the GGO ratio in small lung adenocarcinoma is a good prognostic indicator. Seven studies were combined in a meta-analysis using overall survival (OS) as the end point of interest. The weighted HR of 7 studies was 0.85, with relative 95% CI ranging from 0.78 to 0.93 (P=0.009). For the surgical patient population, the primary endpoint of relapse-free survival (RFS) was superior with high GGO area on computed tomography (The combined HR 0.82, 95% CI 0.74-0.90; P=0.007).

Conclusions: The result of our meta-analysis suggested that the GGO area measured on HRCT had a prognostic value of overall survival and relapse-free survival in small lung adenocarcinoma. The GGO ratio may be an independent prognostic factor for small lung adenocarcinoma.